A linear motor driven crossbeam for processing of a vehicle die-cast frame and a lightweight design method

Abstract

The present application belongs to the technical field of machining tools, and particularly relates to a linear motor driven beam for machining of a vehicle die-cast frame and a lightweight design method. A main beam, an auxiliary beam and a linear motor primary mounting plate are fixedly connected to form a rectangular base frame, and a side plate is closed to form a mouth-shaped torsion-resistant frame. A linear motor secondary mounting plate is fixed to the main beam, and Y-axis guide rail mounting plates are arranged in two on the main beam and one on the auxiliary beam to form three guide rail supports and eliminate load eccentricity. An X-axis guide rail block mounting plate and a bent plate are welded to the lower part of the primary mounting plate to lower the center of gravity. A top plate, a rear plate, a bottom plate and a front plate are connected to form a closed skin, and form a grid structure with internal rib plates. The rib plates are optimally and non-uniformly distributed to support the guide rail mounting plates and the secondary mounting plate and prevent buckling. The three-guide rail layout of the present application reduces the load eccentricity and the torsion angle. The closed mouth-shaped frame improves the bending and torsion stiffness and reduces the overall weight to meet the machining requirements.

Description

Technical Field

[0001] This invention belongs to the field of machine tool technology, specifically relating to a linear motor driven crossbeam for processing vehicle die-cast frames and a lightweight design method. Background Technology

[0002] In the automotive manufacturing industry, the demand for integrated die-cast chassis is growing. These parts are typically large, complex, and require high precision, placing high demands on machining equipment. As one type of machining equipment, a five-axis gantry machining center needs to possess high speed, high acceleration, and high dynamic response capabilities to ensure machining efficiency and accuracy. The crossbeam, as a key functional component of the gantry machining center, has a structural design that determines the overall dynamic performance, rigidity, and stability of the machine.

[0003] Current crossbeams require high stiffness, typically achieved by increasing material thickness or the number of stiffeners. This increases the crossbeam's weight. Due to the increased weight and unreasonable stiffness distribution, the first natural frequency of the crossbeam is low, making it prone to resonance with common excitation frequencies during high-speed motion. This leads to equipment instability and affects processing quality and efficiency. Furthermore, the internal stiffener layout of the crossbeam is mostly longitudinal or transverse, lacking optimized design for torsional stress. During high acceleration, sudden stops, or reversals, torsional deformation can easily occur, affecting the positioning and trajectory accuracy of the end effector. Summary of the Invention

[0004] This invention provides a linear motor-driven crossbeam for processing vehicle die-cast frames, which improves the overall bending and torsional stiffness of the crossbeam. The three-rail support structure eliminates load eccentricity, reduces torsional torque, and improves stability during high-acceleration motion.

[0005] The linear motor driven crossbeam for die-cast vehicle frame processing includes: side plates and main beams and auxiliary beams arranged parallel to each other; Side plates are fixedly connected to both ends of the main beam and both ends of the auxiliary beam to form a U-shaped frame; a linear motor primary mounting plate is connected to the outside of the side plate; the linear motor primary mounting plate, together with the main beam, auxiliary beam and side plate, forms a rectangular closed outer frame. A front panel, top panel, rear panel, and bottom panel are fixedly connected to the rectangular outer frame; the front panel, top panel, rear panel, and bottom panel form a skin structure. The stiffening plates are fixedly connected to the inner wall of the skin structure, dividing the internal cavity of the crossbeam into multiple small units; The linear motor secondary mounting plate is fixed on the inner wall of the main beam, and the front wall of the main beam and the front wall of the auxiliary beam are respectively connected to the Y-axis guide rail mounting plate.

[0006] According to another embodiment of this application, a lightweight design method is provided, the method comprising: S1: Side plates are fixedly connected to both ends of the main beam and both ends of the auxiliary beam to form a rectangular frame. The Y-axis drive mode is configured as a direct drive by a linear motor. Two Y-axis guide rail mounting surfaces are set on the main beam and one Y-axis guide rail mounting surface is set on the auxiliary beam to form a three-guide rail supported Y-axis motion system. S2: The main beam, which includes the Y-axis guide rail mounting plate and the linear motor secondary mounting plate, and the auxiliary beam, which includes the Y-axis guide rail mounting plate, are fixedly connected by the linear motor primary mounting plates and side plates on both sides to form a mouth-shaped anti-torsion frame. S3: Multiple stiffening plates are spaced apart along the length of the crossbeam inside the mouth-shaped anti-torsion frame. The top plate, rear plate, bottom plate, front plate and grating ruler mounting plate are welded to form a skin structure covering the mouth-shaped frame. The stiffening plates are connected to the inner wall of the skin structure and the internal cavity of the crossbeam is divided into multiple small units. Together with the components of the mouth-shaped frame, they form a spatial grid box structure to support the Y-axis guide rail mounting plate and the linear motor secondary mounting plate. S4: On both sides of the rectangular frame, fix the X-axis guide block mounting plate and the bent plate to the linear motor primary mounting plate respectively. Fix the lifting ring mounting plate to the bent plate. Install the entire beam structure onto the X-axis guide rail of the machine tool through the X-axis guide block mounting plate and make the center of gravity of the beam located between the X-axis guide rails. S5: Establish a complete finite element model of the machine, including the crossbeam structure, machine tool slide assembly and spindle components. Perform static and modal characteristic simulation analysis on the complete finite element model to obtain the initial weight of the crossbeam, the first natural frequency and the tool tip offset under the set acceleration. S6: The layout, thickness and spacing of the stiffeners are optimized by topology design. During the optimization process, the load-bearing area under the mouth-shaped anti-torsion frame and the Y-axis guide rail mounting plate is set as the material retention area to strengthen the stiffness of the anti-torsion path and the direct load-bearing area, so as to obtain the final layout of the stiffeners that are not uniformly distributed inside the beam. S7: Based on the final layout of the stiffeners, modify the crossbeam model while keeping the configuration of the main beam, auxiliary beam, guide rail mounting plate, and linear motor mounting plate unchanged. Re-import the modified crossbeam model into the finite element analysis software to perform static and dynamic performance simulation. Verify whether the weight, first natural frequency, and tool tip offset of the updated crossbeam model meet the preset optimization requirements. If they do, manufacture the crossbeam based on the crossbeam model to complete the crossbeam design.

[0007] As can be seen from the above technical solutions, the present invention has the following advantages: This invention features two Y-axis guide rail mounting surfaces on the main beam and one on the auxiliary beam, forming a three-guide rail support system. The main beam and auxiliary beam are rigidly connected by linear motor primary mounting plates and side plates on both sides, forming a closed-mouth anti-torsional frame. The frame has a closed box-shaped cross-section with a torsional moment of inertia higher than that of open or semi-open sections. Multiple stiffening plates are arranged at intervals along the length of the frame, forming a skin around the top plate, rear plate, bottom plate, front plate, and grating ruler mounting plate. The stiffening plates connect to the inner wall of the skin, dividing the cavity into multiple small units, forming a grid box structure. This structure supports the Y-axis guide rail mounting plate and the linear motor secondary mounting plate, preventing local buckling of the wall panels under high loads. In the X-axis direction, the guide rail block mounting plate and the bending plate are fixed to both sides of the linear motor primary mounting plate, and the center of gravity is adjusted by the lifting ring mounting plate, ensuring that the center of gravity of the entire beam falls between the X-axis guide rails.

[0008] This invention establishes a complete finite element model including the crossbeam, slider, and spindle components, and simulates to obtain the initial weight, natural frequency, and tool tip offset. With the goal of increasing the natural frequency, reducing the offset, and matching the torsional resistance requirements of the three guide rails and the jaw frame, topology optimization is performed on the layout, thickness, and spacing of the stiffeners. During optimization, the load-bearing area below the jaw anti-torsion frame and the Y-axis guide rail mounting plate is designated as a material retention area, resulting in non-uniform distribution of stiffener material along the torsional path and in the direct load-bearing area. After modifying the model based on the optimization results, simulations are repeated to verify the results; if the requirements are met, manufacturing proceeds.

[0009] The linear motor drive of this invention eliminates the elastic deformation and critical speed limitation of the lead screw. The three-rail layout constrains the center of gravity of the slide and ram between two rails, reducing torque. The closed-frame design maximizes the torsional moment of inertia of the cross section to the upper limit of a closed structure. Combined with the topology-optimized stiffening material concentrated on the anti-torsional path, the overall torsional stiffness of the beam is improved. The grid box unit distributes the vertical load borne by the guide rail mounting surface to the entire beam wall, avoiding stress concentration and local buckling. With the center of gravity falling between the X-axis rails, the beam no longer generates additional overturning moment during high-speed movement in the X direction, resulting in uniform force on the slider and reduced frictional resistance. Attached Figure Description

[0010] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 Schematic diagram of a linear motor driving a crossbeam for machining a die-cast vehicle frame; Figure 2 Schematic diagram of an embodiment of a linear motor-driven crossbeam for processing vehicle die-cast frames; Figure 3 Schematic diagram of the cross-section of a linear motor driven crossbeam used for machining vehicle die-cast frames; Figure 4 This is a schematic diagram of the finite element method for whole-machine analysis.

[0012] Explanation of reference numerals in the attached figures: 1. Main beam, 2. Auxiliary beam, 3. Y-axis guide rail mounting plate, 4. Linear motor primary mounting plate, 5. Linear motor secondary mounting plate, 6. Grating ruler mounting plate, 7. Lifting ring mounting plate, 8. X-axis guide rail block mounting plate, 9. Side plate, 10. Bend plate, 11. Front plate, 12. Top plate, 13. Rear plate, 14. Rib plate, 15. Bottom plate. Detailed Implementation

[0013] The following describes in detail the linear motor-driven crossbeam for processing vehicle die-cast frames according to this application. Specific details, such as particular system structures and techniques, are presented for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0014] like Figure 1 To be continued Figure 3 As shown, the crossbeam of the present invention includes: side plates 9 and main beam 1 and auxiliary beam 2 arranged parallel to each other. The two ends of the main beam 1 and the two ends of the auxiliary beam 2 are respectively fixedly connected to the side plates 9 to form a U-shaped frame. A linear motor primary mounting plate 4 is connected to the outside of the side plates 9; the linear motor primary mounting plate 4, together with the main beam 1, auxiliary beam 2 and side plates 9, constitute a rectangular closed outer frame.

[0015] It should be noted that the main beam 1 provides a mounting carrier for the Y-axis guide rail mounting plate 3 and the linear motor secondary mounting plate 5, bearing the main load of the Y-axis slide and ram, and can also be used to transmit motion and load. The auxiliary beam 2, together with the main beam 1, forms a double-beam load-bearing structure, assisting the main beam 1 in sharing the Y-axis load, jointly improving the overall bending stiffness of the crossbeam, and forming the main body of the torsional frame with the main beam 1. The linear motor primary mounting plate 4 is used to install the primary components of the linear motor, providing a mounting base for the X-axis linear motor drive. As a side component of the main frame of the crossbeam, the linear motor primary mounting plate, together with the main beam 1, auxiliary beam 2, and side plate 9, forms a closed-type torsional frame, improving the overall torsional stiffness of the crossbeam. The side plate 9 is set along the length of the crossbeam and is welded and fixed to the main beam 1, auxiliary beam 2, and linear motor primary mounting plate 4, strengthening the structural strength of the closed-type torsional frame, improving the overall torsional stiffness of the crossbeam, and suppressing the torsional deformation of the crossbeam under high acceleration conditions.

[0016] Furthermore, a front plate 11, a top plate 12, a rear plate 13, and a bottom plate 15 are fixedly connected to the rectangular outer frame; the front plate 11, the top plate 12, the rear plate 13, and the bottom plate 15 form a skin structure; the stiffening plate 14 is fixedly connected to the inner wall of the skin structure, dividing the internal cavity of the crossbeam into multiple small units.

[0017] The top plate 12 is fixedly connected to the main beam 1, the auxiliary beam 2, and the primary mounting plate 4 of the linear motor; the rear plate 13 is fixedly connected to the rear side wall of the main beam 1, the auxiliary beam 2, and the primary mounting plate 4 of the linear motor; the bottom plate 15 is fixedly connected to the bottom wall of the main beam 1, the auxiliary beam 2, and the primary mounting plate 4 of the linear motor; and the front plate 11 is fixedly connected to the front side wall of the main beam 1, the auxiliary beam 2, and the primary mounting plate 4 of the linear motor.

[0018] It should be noted that the front plate 11 is the front skin component of the crossbeam, which, together with the top plate 12, rear plate 13, and bottom plate 15, forms an externally enclosed box structure, providing an installation base for the grating ruler mounting plate 6. In conjunction with the internal stiffeners 14, it enhances the overall bending and torsional stiffness of the crossbeam, preventing local buckling of the wall panels. The top plate 12, together with the front plate 11, rear plate 13, and bottom plate 15, forms an externally enclosed box structure, which, in conjunction with the internal stiffeners 14, enhances the overall bending and torsional stiffness of the crossbeam, preventing local buckling of the top wall panel. The rear plate 13 is the rear skin component of the crossbeam, which, together with the top plate 12, front plate 11, and bottom plate 15, forms an externally enclosed box structure. In conjunction with the internal stiffeners 14, it enhances the overall bending and torsional stiffness of the crossbeam, preventing local buckling of the rear wall panel. The stiffening plates 14 are spaced along the length of the beam, dividing the internal cavity of the beam into multiple independent small units. Together with the vertical components, they form a spatial grid box structure, strengthening the internal load-bearing capacity and supporting the Y-axis guide rail mounting plate 3 and the linear motor secondary mounting plate 5, preventing local buckling of the wall panels. Non-uniform distribution is achieved through topology optimization, removing redundant mass while ensuring stiffness, improving the beam's stiffness-to-weight ratio, reducing its self-weight, and increasing its first-order natural frequency. The bottom plate 15 is the bottom skin component of the beam, forming an externally closed box structure together with the top plate 12, front plate 11, and rear plate 13. In conjunction with the internal stiffening plates 14, it improves the overall bending and torsional stiffness of the beam, prevents local buckling of the bottom wall panels, and optimizes the stress distribution at the bottom of the beam.

[0019] Furthermore, the secondary mounting plate 5 of the linear motor is fixedly connected to the main beam 1, providing a stable mounting foundation for the secondary of the Y-axis linear motor, reliably transmitting the driving force of the Y-axis linear motor to the slide and ram, ensuring the power transmission efficiency of the Y-axis high-speed and high-acceleration motion, and also transmitting the Y-axis load to the main beam 1, strengthening the load-bearing capacity of the main beam 1.

[0020] The Y-axis guide rail mounting plate 3 is fixedly connected to the main beam 1 and the auxiliary beam 2 to form a three-guide rail support structure. This places the center of gravity of the slide and ram between the two guide rails, completely eliminating the load eccentricity, reducing the torsional torque of the crossbeam, suppressing the torsional deformation of the crossbeam, and improving the stability and positioning accuracy of the Y-axis movement.

[0021] Furthermore, the grating ruler mounting plate 6 is connected to the front plate 11, providing a stable mounting base for the Y-axis grating ruler, ensuring the installation accuracy of the grating ruler, providing reliable position feedback for Y-axis movement, and improving the positioning accuracy and trajectory accuracy of Y-axis movement.

[0022] Furthermore, the lifting ring mounting plate 7 is connected to the bending plate 10 to provide a stable installation foundation for the lifting ring, ensuring uniform stress on the crossbeam during hoisting, transportation, and assembly, avoiding structural deformation of the crossbeam during hoisting, and ensuring the structural accuracy of the crossbeam.

[0023] Furthermore, the X-axis guide block mounting plate 8 is connected to the linear motor primary mounting plate 4, providing a stable mounting base for the X-axis guide slider, reliably mounting the entire crossbeam to the machine tool's X-axis guide, transmitting the X-axis motion load, and ensuring the guiding accuracy of the crossbeam's high-speed, high-acceleration X-axis motion. The X-axis guide block mounting plate 8 is located in the lower middle part of the linear motor primary mounting plate 4, optimizing the overall center of gravity of the crossbeam and improving the stability of high-acceleration motion.

[0024] The bent plate 10 connects to the linear motor primary mounting plate 4 and the X-axis guide block mounting plate 8. The X-axis guide block mounting plate 8 is used to install the X-axis guide slider, mounting the entire crossbeam to the machine tool's X-axis guide, providing guiding support for the X-axis movement of the crossbeam and transmitting the X-axis motion load. The X-axis guide block mounting plate 8 is located in the lower middle part of the side of the crossbeam, optimizing the overall center of gravity of the crossbeam. The bent plate 10 can strengthen the connection strength of the side structure, disperse the load transmitted by the X-axis guide, reduce local stress concentration, and help lower the overall center of gravity of the crossbeam.

[0025] The following are embodiments of the lightweight design method provided in this disclosure. This method belongs to the same inventive concept as the linear motor driven crossbeam for processing vehicle die-cast frames in the above embodiments. For details not described in detail in the embodiments of the lightweight design method, please refer to the embodiments of the linear motor driven crossbeam for processing vehicle die-cast frames described above.

[0026] The method includes the following steps: S1: Side plates 9 are fixedly connected to both ends of the main beam 1 and both ends of the auxiliary beam 2 to form a rectangular frame. The Y-axis drive mode is configured as direct drive by a linear motor. Two Y-axis guide rail mounting surfaces are set on the main beam 1 and one Y-axis guide rail mounting surface is set on the auxiliary beam 2, forming a Y-axis motion system supported by three guide rails.

[0027] In some embodiments, side plates 9 are fixedly connected to both sides of the main beam 1 by submerged arc welding. The Y-axis drive is directly driven by a coreless linear motor. Two parallel Y-axis guide rail mounting surfaces are machined on the main beam 1, and a corresponding Y-axis guide rail mounting surface is machined on the auxiliary beam 2. The mounting surfaces are kept at the same horizontal plane as the guide rail mounting surfaces on the main beam 1, forming a three-guide rail supported Y-axis motion system.

[0028] S2: The main beam 1, which includes the Y-axis guide rail mounting plate 3 and the linear motor secondary mounting plate 5, and the auxiliary beam 2, which includes the Y-axis guide rail mounting plate 3, are fixedly connected by the linear motor primary mounting plates 4 and the side plates 9 on both sides to form a mouth-shaped anti-torsion frame.

[0029] In some embodiments, a Y-axis guide rail mounting plate 3 and a linear motor secondary mounting plate 5 are pre-welded onto the main beam 1. A Y-axis guide rail mounting plate 3 with the same specifications as the main beam is welded onto the auxiliary beam 2, and the installation position corresponds one-to-one with the guide rail mounting plate on the main beam.

[0030] The primary mounting plates 4 of the linear motors on both sides are bolted to the ends of the main beam 1 and the auxiliary beam 2, respectively. Locating pins are added at the connections between the mounting plates and the main and auxiliary beams to ensure connection accuracy. The side plates 9 are rigidly connected to the primary mounting plates 4 of the linear motors, the main beam 1, and the auxiliary beam 2 using a combination of fillet welding and butt welding, ultimately forming a closed, U-shaped torsional frame. When the crossbeam is subjected to torsional moment, the moment is evenly transmitted to the entire frame through the interaction of the main beam, the auxiliary beam, the primary mounting plates of the linear motors, and the side plates, avoiding localized stress concentration.

[0031] The Y-axis guide rail mounting plate and the linear motor secondary mounting plate are key components for load transfer. Their rigid connection with the main beam and auxiliary beam ensures that the load is directly transferred to the frame body, reducing energy loss during load transfer.

[0032] S3: Multiple stiffening plates 14 are spaced apart along the length of the crossbeam inside the mouth-shaped anti-torsion frame. The top plate 12, rear plate 13, bottom plate 15, front plate 11 and grating ruler mounting plate 6 are welded to form a skin structure covering the mouth-shaped frame. The stiffening plates 14 are connected to the inner wall of the skin structure and the internal cavity of the crossbeam is divided into multiple small units. Together with the components of the mouth-shaped frame, they form a spatial grid box structure to support the Y-axis guide rail mounting plate 3 and the linear motor secondary mounting plate 5.

[0033] In some embodiments, multiple stiffening plates 14 are pre-welded along the length of the crossbeam inside the mouth-shaped anti-torsion frame. The width of these plates matches the internal width of the frame, and the height matches the internal height. Each stiffening plate 14 has two 12mm diameter process holes. The length and width of the top plate 12 and bottom plate 15 are consistent with the mouth-shaped frame. The height of the front plate 11 and rear plate 13 matches the frame height. The grating ruler mounting plate 6 is machined with a grating ruler mounting groove, the groove width matching the grating ruler size. The above plates are welded together by submerged arc welding to form a skin structure. After the skin structure covers the mouth-shaped frame, the stiffening plates 14 are fixed to the inner wall of the skin by spot welding, dividing the internal cavity of the crossbeam into multiple small units of uniform size. Finally, together with the mouth-shaped frame components, they form a spatial grid box structure. The bottom of the Y-axis guide rail mounting plate 3 and the linear motor secondary mounting plate 5 are tightly fitted to the top of the stiffening plates 14 and further fixed by bolts.

[0034] In this embodiment, the stiffening plates 14 are spaced apart along the length of the crossbeam, dividing the internal cavity of the crossbeam into multiple small units. Utilizing the distributed stress characteristics of the grid structure, the load transmitted by the guide rail and motor is evenly distributed throughout the entire frame, avoiding structural buckling caused by excessive local stress. The connection between the stiffening plates and the skin further enhances the integrity of the spatial grid structure, making the load transmission path more reasonable and ensuring that the force on the guide rail mounting plate and motor mounting plate can be quickly transmitted to the main frame, avoiding local deformation.

[0035] S4: On both sides of the rectangular frame, fix the X-axis guide block mounting plate 8 and the bending plate 10 to the linear motor primary mounting plate 4 respectively. Fix the lifting ring mounting plate 7 on the bending plate 10. Install the entire beam structure onto the X-axis guide rail of the machine tool through the X-axis guide block mounting plate 8, and make the center of gravity of the beam located between the X-axis guide rails.

[0036] In some embodiments, the X-axis guide block mounting plate and the bent plate serve as connecting components for X-axis movement, rigidly connecting the crossbeam to the machine tool's X-axis guide rail to ensure smooth movement of the crossbeam along the X-axis. The lifting ring mounting plate provides support for the lifting and transportation of the crossbeam, preventing deformation during lifting. Center of gravity optimization, through adjusting the component installation positions and counterweights, ensures the crossbeam's center of gravity falls between the X-axis guide rails. Utilizing the symmetrical support characteristics of the guide rails, this ensures uniform force distribution on both sides of the crossbeam during movement, improving motion stability.

[0037] In some embodiments, the crossbeam of the invention adopts a lightweight box-in-box welded structure, based on a three-rail arrangement, effectively placing the center of gravity of the slide and ram between the two rails of the crossbeam. The calculation formula for the crossbeam's torsional angle θ reveals the anti-torsional mechanism of this design: θ = T·L / (G·It). Where θ is the relative torsional angle between the upper and lower rails of the crossbeam, T is the torque caused by the load gravity, L is the load eccentricity, G is the material shear modulus, and It is the torsional moment of inertia of the cross section. This invention, through the three-rail layout, reduces the load eccentricity L to an extremely low level. The constructed closed-mouth anti-torsional frame and the box-in-box structure form a closed cross section with a high It value, thereby reducing L and increasing It at both ends of the formula, resulting in a synergistic effect that lowers the torsional angle θ.

[0038] Furthermore, the combination of X-axis linear motor drive on both sides and two guide rail support forms a torsional couple, which effectively suppresses the torsional deformation of the frame and improves the torsional stiffness of the crossbeam.

[0039] S5: Establish a complete finite element model of the machine, including the crossbeam structure, the machine tool slide assembly, and the spindle components. Perform static and modal characteristic simulation analysis on the complete finite element model to obtain the initial weight of the crossbeam, the first natural frequency, and the tool tip offset under a set acceleration.

[0040] In some embodiments, by establishing a finite element whole-machine analysis model, planning the layout of the crossbeam guide rails and optimizing the Y-axis guide rail spacing to 660mm, while rationally arranging the reinforcing ribs using a topology optimization method, the dynamic stiffness K in this embodiment is defined as: K=(m*a) / s. Where m is the weight of the crossbeam, a is the X-axis motion acceleration, and s is the tool tip offset. This index reflects the dynamic deformation resistance of the crossbeam under high-speed and high-acceleration conditions. Finally, through simulation verification in step S7, it is confirmed whether the optimized model has achieved the above objectives.

[0041] S6: The layout, thickness and spacing of the stiffeners are optimized by topology design. During the optimization process, the load-bearing area under the shaped anti-torsion frame and the Y-axis guide rail mounting plate is set as the material retention area to strengthen the stiffness of the anti-torsion path and the direct load-bearing area, so as to obtain the final layout of the stiffeners with non-uniform distribution inside the beam.

[0042] S7: Based on the final layout of stiffener 14, modify the crossbeam model while keeping the configuration of the main beam, auxiliary beam, guide rail mounting plate, and linear motor mounting plate unchanged. Re-import the modified crossbeam model into the finite element analysis software to perform static and dynamic performance simulation. Verify whether the weight, first natural frequency, and tool tip offset of the updated crossbeam model meet the preset optimization requirements. If they do, manufacture based on the crossbeam model to complete the crossbeam design.

[0043] Combination Figure 4As shown, the lightweight welded beam design method of the present invention simulates the mechanical response of the beam under actual high-speed and high-acceleration machining conditions, quantifies the machining accuracy of the tool tip, the stiffness and vibration resistance of the beam, provides a benchmark for stiffener topology optimization, and provides a verification basis for final design finalization.

[0044] Figure 4 The medium-length horizontal component corresponds to the lightweight welded crossbeam body of this invention, consisting of a main beam, auxiliary beams, a torsion-resistant frame, a box-in-box skin structure, and topology-optimized stiffeners, etc., and serves as the load-bearing foundation for the entire motion system. The red and blue framed structures above the crossbeam correspond to the machine tool slide assembly, including a slide plate and a slide block, which are mounted on the three Y-axis guide rails of the crossbeam, supporting the spindle components and moving along the Y-axis while simultaneously moving at high speed along the X-axis with the crossbeam.

[0045] The orange structure corresponds to the spindle section, which contains the machining tool and is the end effector used for cutting the integrated die-cast frame of new energy vehicles. The lower end point is the tool tip, and the marked 's' is the offset of the tool tip under load / acceleration, which is an indicator for measuring the machining accuracy of the crossbeam.

[0046] The horizontal arrow ma to the right corresponds to the motion acceleration of the crossbeam along the X-axis, simulating the high-speed, high-acceleration operating conditions in this invention, and is the source of the crossbeam's inertial load.

[0047] Figure 4 Based on structural mechanics and dynamics, and according to Newton's second law F=ma, when the crossbeam moves along the X-axis with acceleration a, the slider and spindle will generate a reverse inertial force. This force acts on the crossbeam, causing bending and torsional deformation, which is eventually transmitted to the tool tip, forming an offset s. In addition to the inertial force, the crossbeam also bears its own weight, the static load of the Y-axis slider, and the dynamic load of the spindle cutting. The deformation under the combined action of multiple loads is the direct source of the tool tip offset s.

[0048] Furthermore, the natural frequency of the structure is positively correlated with stiffness and negatively correlated with the square root of mass. The natural frequency obtained from the simulation directly reflects the vibration resistance of the beam and can quantitatively verify the effect of the stiffness-to-weight ratio improvement after topology optimization.

[0049] As can be seen, this invention eliminates load eccentricity through a three-rail layout along the Y-axis, enhances torsional stiffness through a U-shaped anti-torsional frame, and strengthens the stiffness of the load-bearing area through topology optimization ribs. The ultimate goal is to reduce s and increase the natural frequency. Combined with... Figure 4 The structure was constructed using a three-dimensional parametric model that included a beam, slider, and spindle. The model was matched with the actual assembly relationship. The slider and the Y-axis guide rail of the beam were set to slide in contact, and the spindle and the slider were set to be rigidly bound. After deleting fine structures such as chamfers and process holes, the model was imported into the finite element software.

[0050] Furthermore, actual material parameters are assigned to each component, and the mesh is generated using Solid186 solid elements. The mesh of the concentrated load-bearing areas, such as the Y-axis guide rail installation, is refined to 15mm. Shell181 shell elements are used for the skin, and the mesh distortion rate is controlled to be within 5%, thus generating a finite element model.

[0051] Constraints and loads are applied. Constraints are applied to the mounting position of the X-axis guide rail of the crossbeam, completely restricting the X / Y / Z three-axis displacement and rotation, simulating the support of the machine tool bed on the crossbeam.

[0052] The load can be: ① Apply an acceleration load of 7g along the X-axis, corresponding to arrow a in the figure, to simulate a high-acceleration motion condition; ② Apply a uniformly distributed load of 800N to the mounting surface of the Y-axis guide rail to simulate the weight of the slider assembly; ③ Apply a 1500N negative Z-axis load to the spindle tip to simulate the machining load of the die-casting frame; ④ Apply gravity load to simulate the self-weight of the beam.

[0053] For static simulation, the displacement and stress distribution of the beam under multiple loads are solved, the composite displacement of the tool tip (marked as s in the figure) is extracted, the initial tool tip offset is obtained, and the initial weight of the beam is calculated by volume integration.

[0054] The first 10 modes were extracted using the Block Lanczos method, and the first 3 rigid body modes were ignored to obtain the first natural frequency of the beam, thus completing the acquisition of the initial performance reference parameters.

[0055] Furthermore, based on the initial simulation data, topology optimization was performed on the internal stiffeners of the beam. The area below the torsional frame and the Y-axis guide rail mounting plate was locked as the reserved area. The stiffener layout, thickness and spacing were optimized. After obtaining the non-uniform stiffener layout, the three-dimensional model of the beam was modified. The original stiffeners were deleted and the optimized stiffeners were redrawn, while the core component configuration remained unchanged.

[0056] Furthermore, the modified beam model was re-imported into the finite element software, and static and dynamic simulations were performed again using the exact same constraints, loads, and mesh parameters to extract the optimized tool tip offset s, beam weight, and first-order natural frequency.

[0057] Furthermore, the weight reduction rate, frequency increase rate, and offset reduction rate are calculated. If the weight reduction is ≥35%, the natural frequency increase is ≥30%, and the tool tip offset reduction is ≥30%, then the design requirements are met, and the final beam model is output for manufacturing. If not, the stiffener layout parameters are adjusted, and the simulation verification is repeated until all indicators meet the requirements.

[0058] In some specific embodiments, based on step S5, a complete finite element model of the machine including the beam structure, the machine tool slider assembly and the spindle component is established. The following is a possible embodiment and its specific implementation is described in a non-limiting manner.

[0059] S51: Based on the defined beam model, simplify the local features that do not affect the overall stiffness assessment, including: removing all threaded holes, process holes, small bosses for non-load-bearing purposes, and chamfers and fillets smaller than 5mm; replacing the machine tool's slider assembly and spindle components with equivalent mass points and rotational inertia properties at the center of mass, and connecting the mass points to the corresponding guide rail mounting surfaces or interface surfaces on the beam model through rigid connection units (RBE2).

[0060] S52: Define the model material as high-strength structural steel and set the elastic modulus, Poisson's ratio, and density parameters; define the three-dimensional static cutting force load acting on the mass point of the spindle component based on the typical milling and drilling process parameters of the die-cast frame; define the inertial force load along the X-direction of the beam's motion direction based on the beam's design target acceleration and the total mass of the beam, slider assembly, and spindle component; apply constraints to the connection surface between the X-axis guide block mounting plate and the virtual slider of the machine tool bed, restricting all other degrees of freedom except for the X-direction translational degree of freedom, to simulate the actual motion constraints of the beam on the bed guide rail through the slider.

[0061] S53: Set multiple analysis substeps to simulate different machining stages: First load step, apply gravity load; Second load step, superimpose static cutting force load on the basis of gravity; Third load step, superimpose X-axis high acceleration inertial force load on the basis of the second load step.

[0062] To evaluate the stiffness consistency across the entire length of the beam, the equivalent mass points of the slider assembly and the spindle component were placed at the left, middle, and right ends of the beam's Y-axis guide travel, respectively. For each position, the multi-load step analysis described in S52 was performed to form a simulation condition covering multiple working states.

[0063] In some embodiments, three load steps are defined in the finite element software. Load step 1 activates the gravity load. Load step 2 keeps the gravity load active and activates the static cutting force load. Load step 3 keeps the first two active and activates the X-axis acceleration inertial force load. Each load step is set to a static structural analysis type. The positions of the set of slave nodes connected to the equivalent mass points are changed using a parametric method.

[0064] Specifically, during the modeling phase, three independent sets of rigid connections or interface nodes are created for the slider assembly at three typical positions on the Y-axis guide rail: left, center, and right. During analysis, by replicating the analysis system and replacing different sets of connection nodes, three independent design points are established, each corresponding to a set of connection relationships. This allows for analysis of the slider in the left, center, and right positions. For example, it can be observed that when the slider is at a certain end, the torsional deformation increases due to local structural differences. This provides targeted input conditions and optimization objectives for topology optimization, such as requiring the tip offset to be less than a certain threshold throughout the entire stroke, ensuring that the optimized design improves peak performance and guarantees performance uniformity.

[0065] Furthermore, step S5 also includes the following specific steps: S511: Define the octagonal anti-torsion frame as a named selection set for the beam model. On the mounting surface of the Y-axis guide rail mounting plate, create three independent node groups, corresponding to the stress areas of the two guide rails on the main beam and one guide rail on the auxiliary beam, respectively.

[0066] The overall deformation cloud map of the crossbeam, the maximum deformation of the selected set of the shaped anti-torsion frame, and the average support reaction force of the three guide rail force node groups are extracted as quantitative indicators to evaluate the overall stiffness, anti-torsion frame effectiveness, and force balance of the three guide rails.

[0067] S512: Based on the maximum acceleration and typical motion velocity curves of the crossbeam, calculate the acceleration as a function of time, a(t). Define the X-direction inertial load as a time-varying load function Finertia(t) = mtotal * a(t) that is proportional to a(t), where mtotal is the total mass of the crossbeam and the moving parts it carries.

[0068] Based on typical milling parameters for die-cast aluminum alloys, such as spindle speed n, feed per tooth fz, axial depth of cut ap, and radial width of cut ae, the approximate time histories of the three-dimensional dynamic cutting force components are calculated using the milling force coefficient method and applied synchronously to the mass points of the spindle components in the form of load functions. The analysis time is set to cover a complete motion cycle including acceleration, constant speed, deceleration, and reversal.

[0069] In some embodiments, based on the machine tool servo drive performance, an S-shaped velocity curve from static acceleration to maximum speed Vmax is determined, and its derivative is used to obtain the acceleration time history curve a(t). The a(t) function is input in the form of a list of time-acceleration value pairs. When defining the inertial force load, the formula -mtotal / Volume*a(t) is input in the X component, where Volume is the model volume.

[0070] S513: In the static analysis results of S511, extract the displacement vector of the spindle mass point relative to the machine tool bed under the maximum static cutting force load step, denoted as the static offset s. static In the transient dynamic analysis results of S512, the peak value of the dynamic displacement response curve at the main shaft mass point is extracted during the entire motion cycle and denoted as the dynamic offset s. dynamicpeak The dynamic offset and the static offset are vector-synthesized to obtain an evaluation value s of the overall tool tip offset. combined .

[0071] In some embodiments, static offset is primarily caused by gravity and steady-state cutting force, and constitutes the fundamental error in accuracy. Dynamic offset is the peak value of the vibration response under the excitation of inertial force and dynamic cutting force. While they occur on different timescales, they act together on the workpiece during machining. A simple vector summation is an engineering-conservative but effective evaluation method used to estimate the total error in the worst-case scenario.

[0072] S514: In the modal analysis module, the same boundary conditions as in the static analysis are used, i.e., constraining the five degrees of freedom of the X-axis guide block mounting plate 8 connection surface. The extracted modal order is set to the first 10. After the analysis, the effective mass participation factor (EMF) for each mode is calculated. The two modes with the largest effective torsional mass participation factors are identified, and their natural frequencies f are recorded. torsion1 and f torsion2 Furthermore, the modal animation was compared and analyzed with the deformation morphology of the ulnar anti-torsional frame to confirm the contribution of the frame to improving the torsional modal frequency.

[0073] In some embodiments, the modal analysis setup ensures that the same mesh and constraints as the static analysis are used. Based on the effective mass participation factor and its cumulative value in the six degrees of freedom for each mode, focus on the cumulative effective mass rotating about the X-axis. Identify the top two modes that contribute the most to the cumulative effective torsional mass. Record the natural frequencies of these two modes. Examine the mode shape animations of these two modes, observing whether the area of ​​maximum deformation is concentrated on the U-shaped torsional frame, especially whether relative torsion occurs between the main beam and auxiliary beam. High torsional frequencies require higher excitation energy to induce torsional deformation, making torsional vibration less likely to occur during high-speed, high-acceleration motion. By identifying and extracting key torsional modal frequencies, the dynamic effect of the U-shaped torsional frame in improving torsional stiffness can be directly evaluated. Observing the mode shapes can qualitatively verify whether the frame, as expected, becomes the dominant structure resisting torsional deformation.

[0074] In some specific embodiments, based on step S6, the following will provide a possible embodiment and describe its specific implementation in a non-limiting manner.

[0075] S61: Create a topology optimization task, define all cavity solid meshes inside the beam except for the area below the mouth-shaped anti-torsion frame and the Y-axis guide rail mounting plate 3 as optimizable design domains, define the solid meshes below the mouth-shaped anti-torsion frame and the Y-axis guide rail mounting plate 3 as non-optimizable retention domains, and assign an initial relative density value between 0 and 1 to each element in the optimizable domain.

[0076] Step S61 specifically includes the following steps: S611: In the finite element software, select all solid elements of the entire beam, set the element type to an eight-node hexahedron, assign an initial relative density value of 1.0 to each element in the material property definition, and set this state as the optimization starting point.

[0077] In some embodiments, an initial density of 1.0 indicates that the design domain is completely filled with solid material, and the optimization process gradually removes low-contribution elements. Eight-node hexahedral elements offer higher computational accuracy than tetrahedral elements and are suitable for stress analysis of beam structures.

[0078] S612: Based on the assembly drawing of the crossbeam, create three unit sets: the first set contains the units of the main beam 1, the auxiliary beam 2, the primary mounting plates 4 of the linear motors on both sides, and the side plate 9; The second set contains two rows of units along the thickness direction below the Y-axis guide rail mounting plate 3; The third set includes all units of the top plate 12, rear plate 13, bottom plate 15, and front plate 11; The three sets mentioned above are removed from the optimizable domain and assigned to the reserved domain. In the optimization settings, the density value of the reserved domain cells is permanently locked to 1.0.

[0079] In some embodiments, the orifice-shaped anti-torsional frame forms a closed annular cross-section of the beam, with a torsional moment of inertia much higher than that of an open cross-section, making it the main structure resisting torsional deformation of the beam. Below the Y-axis guide rail mounting plate is the direct transmission path of the slider force; any material removal in this area will lead to a decrease in the local stiffness of the guide rail mounting surface, thus affecting the straightness of the Y-axis movement. The skin plate and stiffeners together form a box-within-a-box structure; if the skin is optimized, it will result in an open cross-section and a significant loss of torsional stiffness. Therefore, these three areas are designated as reserved regions.

[0080] S613: At the interface between the optimizable domain and the reserved domain, a transition layer with a thickness of one cell size is set. The initial relative density value of the cells in the transition layer is linearly changed from 1.0 on the reserved domain side to 1.0 inside the optimizable domain. The cells in the reserved domain are also excluded from the sensitivity calculation list so that they do not participate in the density update of each iteration.

[0081] In some embodiments, the thickness of the transition layer is set to the average size of one cell. The initial relative density value of each cell within the transition layer is calculated linearly according to its distance from the surface of the retention domain: density = 1.0 at a distance of 0, density = 1.0 at a distance equal to the transition layer thickness, meaning the density within the transition layer remains at 1.0 and does not decrease. Since the density of the retention domain is locked at 1.0, the density within the optimizable domain is also 1.0. The role of the transition layer is to avoid numerical discontinuities caused by abrupt density changes. By setting the transition layer, the mechanical continuity between the optimizable and retention domains is ensured during the optimization process, making the optimization results more consistent with real-world scenarios.

[0082] S62: Set the optimization objective as a weighted combination function, where the tool tip displacement term takes the composite displacement value from the static analysis, and the first-order natural frequency term takes the frequency value from the modal analysis. Set the weight coefficient of the tool tip displacement to 0.6 and the weight coefficient of the first-order natural frequency to 0.4. Set the constraint condition that the final volume retention percentage of the optimizable domain is 30% to 40% of the original volume, and apply a lower limit constraint that the first-order natural frequency is not lower than 80% of the initial frequency.

[0083] In some embodiments, multi-objective optimization transforms different objectives into a single scalar function through weighted combination. The weight coefficients reflect the degree of importance given to the two objectives, with the allocation of 0.6 and 0.4 based on empirical settings.

[0084] S63: Call the topology optimization solver and use the optimization criterion algorithm to iteratively update the cell density. After each iteration, calculate the current objective function value. If the rate of change of the objective function between two adjacent iterations is less than 1%, it is determined to be converged. Otherwise, continue iterating. During the iteration process, density filtering is performed every 5 steps to eliminate the checkerboard effect, and projection filtering is performed every 10 steps to obtain a clear 0 / 1 distribution.

[0085] S64: After the iteration converges, the density threshold is set to 0.5 in the post-processing of the results. All elements with a density greater than 0.5 are extracted to generate contour surfaces. The contour surfaces are then transformed into smooth NURBS surfaces. Finally, the surface is thickened to generate a solid model of stiffeners with continuous geometric contours. In the solid model of stiffeners, the stiffeners are arranged in a non-uniform distribution along the main load-bearing path.

[0086] In some embodiments, topology optimization outputs the element density distribution, with a density value of 0.5 as the binarization threshold; values ​​above 0.5 indicate the presence of material, while values ​​below 0.5 indicate the absence of material. Isosurface extraction transforms the discrete density field into a continuous geometric surface. Contour extraction and lofting operations convert the curved shell into a solid rib with thickness, 6-10 mm, corresponding to common welded steel plate specifications, meeting welding process requirements and avoiding buckling caused by excessive thinness.

[0087] In some specific embodiments, based on step S7, the following will provide a possible embodiment and describe its specific implementation in a non-limiting manner.

[0088] S71: Delete all geometric surfaces of the original stiffener in the 3D modeling software, import the stiffener solid model generated in step S64, align the spatial coordinate system of the stiffener model with the original model, make the outer contour surface of the stiffener fit with the inner wall surface of the reserved domain, perform Boolean union operation, and generate the modified beam model.

[0089] In some embodiments, in SolidWorks, all stretching or array features corresponding to the stiffener are located, and the stiffener solid model generated in step S64 is browsed and imported. The origin of the stiffener model's coordinate system is aligned with the origin of the original model's global coordinate system so that each face of the stiffener fits against the inner walls of the main beam, auxiliary beam, top plate, bottom plate, front plate, and rear plate.

[0090] S72: Create a new analysis project in the finite element software, import the modified beam model, re-mesh based on the preset global element size and local refinement size, and apply displacement constraints and force loads.

[0091] In some embodiments, finite element mesh generation uses tetrahedral or hexahedral elements to fill the geometry, with element size controlling the global mesh density and local refinement ensuring solution accuracy in stress concentration regions. Material properties define the elastic matrix and mass matrix in the constitutive relation.

[0092] S73: Read the composite displacement value of the blade tip position, the frequency value of the first-order bending mode, and the total volume, and multiply them by the density to obtain the offset of the blade tip Sfinal under the same acceleration after optimization, the first-order natural frequency ffinal of the optimized crossbeam, and the final weight mfinal of the optimized crossbeam.

[0093] S74: Calculate the weight reduction rate ηm=(minitial-mfinal) / minitial, the frequency increase rate ηf=(ffinal-finitial) / finitial, and the offset reduction rate ηs=(sinitial-sfinal) / sinitial; minitial is the initial weight of the crossbeam before optimization, finitial is the first natural frequency of the crossbeam before optimization, and sinitial is the offset of the tool tip point under the set acceleration before optimization.

[0094] If ηm≥35% and ηf≥30% and ηs≥30%, then output the final beam model; if not, return to step S62, reduce the volume constraint percentage by 5 percentage points, and re-execute steps S63 and S64 to verify again.

[0095] In some embodiments, weight reduction rate, frequency increase rate, and offset reduction rate are three performance metrics, and comparing them with the initial values ​​eliminates the influence of model scale. When these targets are not met, stiffness is increased by reducing the percentage of volume constraints, but this affects the weight reduction effect, creating a trade-off. The iterative cycle continues until all targets are met, ensuring that the final design meets the requirements.

[0096] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0097] It should be understood that when an element or layer is referred to as being "connected" or "coupled" to another element or layer "on" it may be directly connected or coupled to said other element or layer, or there may be intermediate elements or layers. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element or layer "on" it is not an intermediate element or layer. Similar figures in all figures indicate similar elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0098] Spatially relative terms such as “below,” “under,” “lower,” “above,” “above,” etc., may be used here to describe the relationship between one element or feature and another, as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation other than those shown in the figure. For example, if the device in the figure were flipped over, the element described as “below” or “under” other elements or features would be facing “above” other elements or features. Thus, the exemplary term “below” can include both above and below orientations. Other orientations (rotation 90 degrees or other orientations) may be adopted, and the spatially relative terms used herein will be interpreted accordingly.

[0099] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the expression within this document. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that, when used in this specification, the term “comprising” means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0100] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lightweight design method, characterized in that the method include: S1: Side plates (9) are fixedly connected to both ends of the main beam (1) and both ends of the auxiliary beam (2) to form a rectangular frame. The Y-axis drive mode is configured as a direct drive of a linear motor. Two Y-axis guide rail mounting surfaces are set on the main beam (1) and one Y-axis guide rail mounting surface is set on the auxiliary beam (2) to form a Y-axis motion system supported by three guide rails. S2: The main beam (1) containing the Y-axis guide rail mounting plate (3) and the linear motor secondary mounting plate (5) is fixedly connected to the auxiliary beam (2) containing the Y-axis guide rail mounting plate (3) through the linear motor primary mounting plates (4) and side plates (9) on both sides to form a mouth-shaped anti-torsion frame. S3: Multiple stiffeners (14) are spaced apart along the length of the crossbeam inside the mouth-shaped anti-torsion frame. The top plate (12), rear plate (13), bottom plate (15), front plate (11) and grating ruler mounting plate (6) are welded to form a skin structure covering the mouth-shaped frame. The stiffeners (14) are connected to the inner wall of the skin structure and the internal cavity of the crossbeam is divided into multiple small units. Together with the components of the mouth-shaped frame, they form a spatial grid box structure to support the Y-axis guide rail mounting plate (3) and the linear motor secondary mounting plate (5). S4: On both sides of the rectangular frame, fix the X-axis guide block mounting plate (8) and the bent plate (10) to the linear motor primary mounting plate (4) respectively. Fix the lifting ring mounting plate (7) on the bent plate (10). Install the entire beam structure onto the X-axis guide rail of the machine tool through the X-axis guide block mounting plate (8) and make the center of gravity of the beam located between the X-axis guide rails. S5: Establish a complete finite element model of the machine, including the crossbeam structure, machine tool slide assembly and spindle components. Perform static and modal characteristic simulation analysis on the complete finite element model to obtain the initial weight of the crossbeam, the first natural frequency and the tool tip offset under the set acceleration. S6: The layout, thickness and spacing of the stiffener (14) are optimized by topology design. During the optimization process, the bearing area under the mouth-shaped anti-torsion frame and the Y-axis guide rail mounting plate (3) is set as the material retention area to strengthen the stiffness of the anti-torsion path and the direct bearing area, so as to obtain the final layout of the stiffener with non-uniform distribution inside the beam. S7: Based on the final layout of the stiffeners, modify the crossbeam model while keeping the configuration of the main beam, auxiliary beam, guide rail mounting plate, and linear motor mounting plate unchanged. Re-import the modified crossbeam model into the finite element analysis software to perform static and dynamic performance simulation. Verify whether the weight, first natural frequency, and tool tip offset of the updated crossbeam model meet the preset optimization requirements. If they do, manufacture the crossbeam based on the crossbeam model to complete the crossbeam design.

2. The lightweight design method according to claim 1, characterized in that, Step S5, establishing the complete machine finite element model including the beam structure, machine tool slide assembly, and spindle components, specifically includes the following steps: S51: The crossbeam model is geometrically simplified, local small features are removed, and the slider assembly and spindle component are equivalent to mass points, which are then connected to the guide rail mounting surface of the crossbeam through rigid connection units; S52: Define the beam material as high-strength structural steel, apply a triaxial static cutting force load and an X-axis inertial force load, and apply constraints to the connection surface between the X-axis guide block mounting plate and the virtual slider of the machine tool bed, restricting all degrees of freedom except for the X-axis translational degree of freedom; S53: Set multiple load steps with gravity, static cutting force, and high acceleration inertial force superimposed in sequence, and place the equivalent mass points of the slider and the spindle at the left, middle, and right ends of the Y-axis guide travel of the crossbeam, respectively, to form multiple simulation conditions to evaluate the consistency of stiffness along the entire length.

3. The lightweight design method according to claim 1, characterized in that, In step S5, static and modal characteristic simulation analysis is performed on the finite element model of the whole machine to obtain the initial weight of the crossbeam, the first natural frequency, and the offset of the tool tip under the set acceleration. Specifically, this includes the following steps: S511: Define the lip-shaped anti-torsion frame as a named selection set in the beam model, and create three node groups on the mounting surface of the Y-axis guide rail mounting plate. Extract the overall deformation cloud map, the maximum deformation of the lip-shaped anti-torsion frame, and the average support reaction force of the three node groups to evaluate the overall stiffness, anti-torsion frame performance, and the force balance of the three guide rails. S512: Calculate the time-varying function of acceleration based on the maximum acceleration and motion speed curve of the crossbeam design, define the X-axis inertial force load as a function proportional to the time-varying acceleration, and calculate the three-axis cutting force time history based on milling parameters. Apply the load function synchronously to the spindle mass point, and analyze the time covering a complete motion cycle. S513: Extract the offset vector of the spindle mass point from the static analysis results under constant cutting force load step as constant load offset, and extract the peak value of the displacement response curve of the spindle mass point in the entire motion cycle from the time-varying load response analysis results as the peak value of time-varying load offset. Combine the two vectors to obtain the comprehensive tool tip offset evaluation value. S514: In modal analysis, the same boundary conditions as in static analysis are used to extract the first ten modes, calculate the effective torsional mass participation factor of each mode around the X-axis, identify the two modes with the largest torsional mass participation factors and record their natural frequencies, and compare and analyze the deformation morphology of the mode shape with that of the ulnar anti-torsional frame.

4. The lightweight design method according to claim 1, characterized in that, Step S6 specifically includes the following steps: S61: Create a topology optimization task, define all cavity solid meshes inside the beam except for the area below the mouth-shaped anti-torsion frame and the Y-axis guide rail mounting plate (3) as optimizable design domains, define the solid meshes below the mouth-shaped anti-torsion frame and the Y-axis guide rail mounting plate (3) and all skin plates as non-optimizable retention domains, and assign an initial relative density value between 0 and 1 to each element in the optimizable domain. S62: Set the optimization objective as a weighted combination function, where the tool tip displacement term takes the composite displacement value from the static analysis, and the first-order natural frequency term takes the frequency value from the modal analysis. Set the weight coefficient of the tool tip displacement to 0.6 and the weight coefficient of the first-order natural frequency to 0.

4. Set the constraint condition that the final volume retention percentage of the optimizable domain is 30% to 40% of the original volume, and apply a lower limit constraint that the first-order natural frequency is not lower than 80% of the initial frequency. S63: Call the topology optimization solver and use the optimization criterion algorithm to iteratively update the cell density. After each iteration, calculate the current objective function value. If the rate of change of the objective function between two adjacent iterations is less than 1%, it is determined to be converged. Otherwise, continue iterating. During the iteration process, density filtering is performed every 5 steps to eliminate the checkerboard effect, and projection filtering is performed every 10 steps to obtain a clear 0 / 1 distribution. S64: After the iteration converges, the density threshold is set to 0.5 in the post-processing of the results. All elements with a density greater than 0.5 are extracted to generate contour surfaces. The contour surfaces are then transformed into smooth NURBS surfaces. Finally, the surface is thickened to generate a solid model of stiffeners with continuous geometric contours. In the solid model of stiffeners, the stiffeners are arranged in a non-uniform distribution along the main load-bearing path.

5. The lightweight design method according to claim 1, characterized in that, S61 specifically includes the following steps: S611: In the finite element software, select all solid elements of the entire beam, set the element type to an eight-node hexahedron, assign an initial relative density value of 1.0 to each element in the material property definition, and set the state to the optimization starting point; S612: Based on the assembly drawing of the crossbeam, create three unit sets: the first set contains the units of the main beam (1), the auxiliary beam (2), the primary mounting plates (4) of the linear motors on both sides, and the side plates (9); The second set contains two rows of units along the thickness direction below the Y-axis guide rail mounting plate (3); The third set includes all units of the top plate (12), rear plate (13), bottom plate (15), and front plate (11); Remove the above three sets from the optimizable domain and assign them to the reserved domain, and permanently lock the density value of the reserved domain cells to 1.0 in the optimization settings; S613: At the interface between the optimizable domain and the reserved domain, a transition layer with a thickness of one cell size is set. The initial relative density value of the cells in the transition layer is linearly changed from 1.0 on the reserved domain side to 1.0 inside the optimizable domain. The cells in the reserved domain are also excluded from the sensitivity calculation list so that they do not participate in the density update of each iteration.

6. The lightweight design method according to claim 1, characterized in that, S7 specifically includes the following steps: S71: Delete all geometric surfaces of the original stiffener in the 3D modeling software, import the stiffener solid model generated in step S64, align the spatial coordinate system of the stiffener model with the original model, make the outer contour surface of the stiffener fit with the inner wall surface of the reserved domain, perform Boolean union operation, and generate the modified beam model. S72: Create a new analysis project in the finite element software, import the modified beam model, re-mesh based on the preset global element size and local refinement size, and apply displacement constraints and force loads; S73: Read the composite displacement value of the tool tip position, the frequency value of the first-order bending mode, the total volume, and multiply it by the density to obtain the offset of the tool tip Sfinal under the same acceleration after optimization, the first-order natural frequency ffinal of the optimized crossbeam, and the final weight mfinal of the optimized crossbeam. S74: Calculate the weight reduction rate ηm=(minitial-mfinal) / minitial, the frequency increase rate ηf=(ffinal-finitial) / finitial, and the offset reduction rate ηs=(sinitial-sfinal) / sinitial; minitial is the initial weight of the crossbeam before optimization, finitial is the first natural frequency of the crossbeam before optimization, and sinitial is the offset of the tool tip point under the set acceleration before optimization; If ηm≥35%, ηf≥30%, and ηs≥30%, then output the final beam model; if not, return to step S62, reduce the volume constraint percentage by 5 percentage points, and re-execute steps S63 and S64 to verify again.

7. A linear motor driven crossbeam for machining a vehicle die-cast frame, characterized in that, The linear motor driven crossbeam for processing the vehicle die-cast frame is designed based on the lightweight design method described in any one of claims 1 to 6. The crossbeam includes: side plates (9) and main beams (1) and auxiliary beams (2) arranged in parallel to each other; Side plates (9) are fixedly connected to both ends of the main beam (1) and the auxiliary beam (2) respectively, forming a mouth-shaped frame; the side plates (9) are connected to the external linear motor primary mounting plate (4); the linear motor primary mounting plate (4) together with the main beam (1), the auxiliary beam (2) and the side plates (9) form a rectangular closed outer frame. A front plate (11), a top plate (12), a rear plate (13), and a bottom plate (15) are fixedly connected to the rectangular outer frame; the front plate (11), the top plate (12), the rear plate (13), and the bottom plate (15) form a skin structure; The stiffening plate (14) is fixedly connected to the inner wall of the skin structure, dividing the internal cavity of the beam into multiple small units; The linear motor secondary mounting plate (5) is fixed on the inner side wall of the main beam (1), and the front side wall of the main beam (1) and the front side wall of the auxiliary beam (2) are respectively connected to the Y-axis guide rail mounting plate (3).

8. The linear motor driven crossbeam for processing vehicle die-cast frames according to claim 7, characterized in that, The top plate (12) is fixedly connected to the main beam (1), the auxiliary beam (2) and the linear motor primary mounting plate (4) respectively; The rear plate (13) is fixedly connected to the rear side wall of the main beam (1), the auxiliary beam (2) and the primary mounting plate (4) of the linear motor respectively; The base plate (15) is fixedly connected to the bottom wall of the main beam (1), the auxiliary beam (2) and the primary mounting plate (4) of the linear motor respectively; The front plate (11) is fixedly connected to the front side wall of the main beam (1), the auxiliary beam (2) and the linear motor primary mounting plate (4).

9. The linear motor driven crossbeam for processing vehicle die-cast frames according to claim 8, characterized in that, A grating ruler mounting plate (6) is fixedly connected to the front side wall of the front plate (11); A lifting ring mounting plate (7) is fixedly connected to the outer wall of the curved plate (10).

10. The linear motor driven crossbeam for processing vehicle die-cast frames according to claim 8, characterized in that... An X-axis guide block mounting plate (8) is provided on the outer side wall of the linear motor primary mounting plate (4) near the middle and lower part; The curved plate (10) is fixedly connected to the outer wall of the linear motor primary mounting plate (4) and the X-axis guide block mounting plate (8) respectively.

Images