A Structural Design Method for a Large Press

Abstract

The present invention discloses a structural design method for a large press, which comprises the following steps: roughly designing the press; testing and measuring the stiffness and strength of the slider, column and workbench in the press; performing simulation analysis on the press model and the workpiece forming process, comparing and analyzing with the experimental results, and adjusting the simulation model according to the experimental results and the workpiece forming simulation effect; performing topology optimization on the fuselage based on dynamic loads to obtain an optimized fuselage model; the present invention uses dynamic tests to achieve the dynamic stress and dynamic displacement tests of the fuselage, and adjusts the simulation model according to the dynamic loads to ensure the dynamic accuracy index of the design.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical design, and particularly to a structural design method for a large press. Background Art

[0002] In the traditional press design process, the general shape of the fuselage is designed based on experience and technical requirements, processed, and experiments are carried out on the prototype. Problems such as insufficient strength and stiffness at key parts may occur, prolonging the product design cycle and resulting in high design costs. To solve the above problems, in the prior art, a Chinese invention patent with the title "An Optimization Design Method for the Body of a Lightweight Stiffness Fine Blanking Press" and publication number CN 102096748 A and publication date June 15, 2011 is disclosed. It includes the following steps: rough design of the body of the fine blanking press; judging whether there is room for optimization of the rough design model based on the strain nephogram and stress nephogram of the roughly designed body, optimizing the stiffness and natural frequency of the rough body, finding the optimization space for stiffness and natural frequency, topologically optimizing the size optimization of the body, and using the size optimization of the model body to obtain the optimized model of the body of the fine blanking press. It mainly conducts simulation analysis, uses the static and dynamic strength and stiffness performance obtained in the simulation analysis as indicators, and mainly modifies the parameters in the simulation model with empirical values during the simulation process to conduct design analysis and optimization of the press. It fails to consider the influence of actual dynamic load performance on the press, and at the same time, without experimental support, it is impossible to guarantee the dynamic accuracy of the press. Summary of the Invention

[0003] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the specification of this application, to avoid obscuring the purpose of this part, the abstract of the specification, and the title of the invention. However, such simplifications or omissions cannot be used to limit the scope of the present invention.

[0004] In view of the above and / or existing problems in the design of presses, the present invention is proposed.

[0005] Therefore, the purpose of the present invention is to provide a structural design method for a large press, which uses dynamic tests to achieve dynamic stress and dynamic displacement tests of the fuselage, adjusts the simulation model according to dynamic loads, ensures the dynamic accuracy index of the design, and minimizes costs.

[0006] To solve the above technical problems, the present invention provides the following technical solution: A structural design method for a large press, which includes the following steps:

[0007] Conduct a rough design of the press;

[0008] Test the stiffness and strength of the slider, columns, and workbench in the test press;

[0009] Simulate and analyze the press model and the workpiece forming process, compare and analyze with the experimental results, and adjust the simulation model (constraints, contacts, meshes, loading curves) according to the experimental results and the simulation effect of the workpiece forming;

[0010] Perform topology optimization on the fuselage based on dynamic loads to obtain the optimized fuselage model.

[0011] As a preferred solution of the large - press structure design method described in the present invention, the test steps are as follows:

[0012] Attach resistance strain gauges to the workbench, slider, columns, and crossbeam respectively;

[0013] Arrange displacement sensors on the crossbeam, workbench, and slider;

[0014] Place several simulated hydraulic cylinders on the workbench;

[0015] Start the press to conduct dynamic stress tests on the simulated hydraulic cylinder stamping. The strain gauge collects the dynamic stress of each measuring point, and the displacement sensor collects the dynamic displacement of each measuring point.

[0016] As a preferred solution of the large - press structure design method described in the present invention, through the dynamic stress test of the press, it is obtained that the dynamic stress changes with time. The entire fuselage is subjected to the combined action of the stamping force and the inertial force during stamping. Compare the maximum value of the dynamic stress with the finite - element analysis result, and adjust the simulation model according to the maximum value of the dynamic stress.

[0017] As a preferred solution of the large - press structure design method described in the present invention, before the dynamic stress test, conduct a static stress test on the workpiece. Specifically:

[0018] Press the slider on the workpiece, gradually load the press, and each acquisition point is collected 3 times during the loading process. Finally, take the average value of the 3 times as the strain value of each acquisition point;

[0019] Calculate the equivalent stress of each acquisition point using the fourth - strength theory;

[0020] The displacement sensor collects the static displacement of each measuring point.

[0021] As a preferred solution of the large - press structure design method described in the present invention, during the dynamic stress test, take the location with relatively large static stress in each part of the fuselage as the measuring point of the dynamic stress. Obtain the calibration value of the corresponding channel through the strain amplifier, calculate the dynamic strain of each measuring point, and obtain the stress value of each measuring point.

[0022] As a preferred embodiment of the structural design method of the large press of the present invention, wherein: the calculation formula for the dynamic strain of the measurement point is

[0023]

[0024] wherein, the waveform peak value is the peak value of the resistance signal wave generated by the resistance strain gauge collected during the dynamic stress test.

[0025] Compared with the prior art, the present invention has the following technical effects: The present invention uses dynamic tests to realize the dynamic stress and dynamic displacement tests of the machine body, and adjusts the simulation model according to the dynamic load to ensure the dynamic accuracy index of the design, improve the stamping accuracy of the press, and minimize the cost. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0027] Figure 1 It is the front view of the present invention.

[0028] Figure 2 It is the three-dimensional structure diagram of the present invention during the test.

[0029] Figure 3 It is the structure diagram of the present invention simulating the distribution of hydraulic cylinders on the upper side of the workbench during the test.

[0030] Figure 4 It is the measurement point distribution diagram of the lower surface of the crossbeam in the present invention.

[0031] Figure 5 It is the measurement point distribution diagram of the upper surface of the crossbeam in the present invention.

[0032] Figure 6 It is the measurement point distribution diagram of the mandrel hole and the weld on the right side of the crossbeam in the present invention.

[0033] Figure 7 It is the measurement point distribution diagram of the upper surface of the slider in the present invention.

[0034] Figure 8 It is the measurement point distribution diagram of the front and rear surfaces of the slider in the present invention.

[0035] Figure 9 It is the measurement point distribution diagram of the left and right surfaces of the slider in the present invention.

[0036] Figure 10 It is the measurement point distribution diagram of the front and rear surfaces of the base in the present invention.

[0037] Figure 11 This is the distribution diagram of measuring points on the front and rear surfaces of the workbench in the present invention.

[0038] Figure 12 This is the distribution diagram of stress measuring points on the left front column in the present invention.

[0039] Figure 13 This is the distribution diagram of stress measuring points on the right front column in the present invention.

[0040] Figure 14 This is the distribution diagram of stress measuring points on the left rear column in the present invention.

[0041] Figure 15 This is the distribution diagram of stress measuring points on the right rear column in the present invention.

[0042] Figure 16 This is the schematic diagram of the bidirectional strain gauge in the present invention.

[0043] Figure 17 This is the waveform diagram of the measuring point signal when measuring dynamic stress under dynamic loading on the column.

[0044] Figure 18 This is the waveform diagram of the measuring point signal when measuring dynamic stress under dynamic loading on the slider.

[0045] Figure 19 This is the waveform diagram of the measuring point signal when measuring dynamic stress under dynamic loading on the workbench.

[0046] Figure 20 This is the stress diagram under the pure shear stress state.

[0047] Figure 21 This is the stress diagram under the principal stress state.

[0048] In the figure, 100 is the left front column, 200 is the slider, 300 is the crossbeam, 400 is the stamping hydraulic cylinder, 500 is the right front column, 600 is the workbench, 700 is the base, 800 is the left rear column, and 900 is the right rear column. Specific embodiments

[0049] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given in conjunction with the accompanying drawings of the specification.

[0050] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0051] Second, as used herein, "an embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in an embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that is mutually exclusive with other embodiments.

[0052] Embodiment 1

[0053] Referring to Figure 1 , which is the first embodiment of the present invention. This embodiment provides a structural design method for a large press, which uses dynamic tests to achieve dynamic stress and dynamic displacement tests of the machine body, and adjusts the simulation model according to the dynamic load to ensure the dynamic accuracy index of the design.

[0054] A structural design method for a large press includes the following steps:

[0055] Roughly design the press;

[0056] Test the stiffness and strength of the slider 200, columns, and workbench 600 in the press;

[0057] Perform simulation analysis on the press model and the workpiece forming process, compare with the experimental results, and adjust simulation parameters such as constraints, contacts, meshes, and loading curves of the simulation model according to the experimental results and the simulation effect of workpiece forming, so that the simulation results approach the experimental results;

[0058] Perform topology optimization on the machine body based on dynamic loads to obtain an optimized machine body model.

[0059] The test steps are as follows:

[0060] Attach resistance strain gauges to the workbench 600, slider 200, columns, and crossbeam 300 respectively;

[0061] Arrange displacement sensors on the crossbeam 300, workbench 600, and slider 200;

[0062] Place several simulated hydraulic cylinders on the workbench 600;

[0063] Start the press to perform dynamic stress tests on the simulated hydraulic cylinders. The strain gauge collects the dynamic stress of each measuring point, and the displacement sensor collects the dynamic displacement of each measuring point.

[0064] Furthermore, through the dynamic stress test of the press, it is obtained that the dynamic stress changes with time. The entire machine body is subjected to the combined action of the punching force and the inertial force during stamping. Take the maximum value of the dynamic stress and compare it with the finite element analysis result, and adjust the simulation model according to the maximum value of the dynamic stress.

[0065] Further, before the dynamic stress test, a static stress test is performed on the workpiece. Specifically,

[0066] Press the slider 200 against the workpiece, gradually load the press, collect data 3 times at each acquisition point during the loading process, and finally take the average of the 3 times as the strain value of each acquisition point;

[0067] Calculate the equivalent stress of each acquisition point using the fourth strength theory;

[0068] The displacement sensor collects the static displacements of each measuring point.

[0069] Further, during the dynamic stress test, select the locations with relatively large static stress in each part of the fuselage as the measuring points for dynamic stress. Obtain the calibration values of the corresponding channels through a strain amplifier as shown in Table 1, calculate the dynamic strain of each measuring point, and obtain the stress values of each measuring point.

[0070] Table 1 Calibration values corresponding to each channel

[0071] Channel number Calibration value Channel number Calibration value Channel 1 504 Channel 9 504 Channel 2 505 Channel 10 504 Channel 3 504 Channel 11 503 Channel 4 504 Channel 12 504 Channel 5 503 Channel 13 504 Channel 6 504 Channel 14 504 Channel 7 504 Channel 15 504 Channel 8 503 Channel 16 504

[0072] The calculation formula for the dynamic strain of the measuring point is:

[0073]

[0074] Among them, the waveform peak value is the peak value of the resistance signal wave generated by the resistance strain gauge collected during the dynamic stress test.

[0075] The overall structure of the press includes a base 700. Four sides of the upper side of the base 700 are respectively fixed with a left front column 100, a right front column 500, a left rear column 800, and a right rear column 900. The upper sides of the left front column 100, the right front column 500, the left rear column 800, and the right rear column 900 are fixed with a cross beam 300. A number of stamping hydraulic cylinders 400 are arranged on the lower side of the cross beam 300. A stamping rod is connected to the stamping hydraulic cylinder 400. The slider 200 is only shown schematically in the figure and is fixed to the lower side of the stamping rod.

[0076] The present invention uses a dynamic test to realize the dynamic stress and dynamic displacement tests of the fuselage, adjusts the simulation model according to the dynamic load, ensures the dynamic accuracy index of the design, improves the stamping accuracy of the press, and reduces the cost to the lowest; it is applicable to the design work of large presses.

[0077] Embodiment 2

[0078] Refer to Figures 2 to 19 , which is the second embodiment of the present invention. The difference between this embodiment and Embodiment 1 is that this embodiment provides a structural design method for a large press, and uses specific tests to verify the results of the dynamic test.

[0079] A structural design method for a large - scale press. When testing static stress, 16 hydraulic cylinders are arranged in 2 rows on the upper side of the workbench 600, as Figure 2 and Figure 3 shown. The static stress loading conditions are shown in Table 2.

[0080] Table 2 Static stress test loading conditions

[0081] Loading percentage Loading tonnage t <![CDATA[Cylinder area / cm 2 > Quantity <![CDATA[Total area of the oil cylinder / cm 2 > Cylinder oil pressure / MPa 20％ 200 314 16 5024 3.98 40％ 400 314 16 5024 7.96 60％ 600 314 16 5024 11.94 80％ 800 314 16 5024 15.92 100％ 1000 314 16 5024 19.90

[0082] Strain gauges are pasted on the lower surface of the crossbeam 300, as Figure 4 shown. Unidirectional gauges are pasted at the measuring points L1 - L10. The measuring points are arranged along the length direction of the side line. Bidirectional gauges are pasted at the measuring points HD1 - HD9. Strain gauges are pasted on the upper surface of the crossbeam 300 as Figure 5 shown. Specifically, unidirectional gauges are pasted at the measuring points LS1 - LS6; Strain gauges are pasted at the core shaft holes and weld measuring points on the right side surface of the crossbeam 300 as Figure 6 shown. The measuring points K, KS and F series are all bidirectional gauges. The F series is arranged at a 45° angle with the weld.

[0083] Strain gauges are pasted on the upper surface of the slider 200 as Figure 7 shown. The measuring points HU1 - HU8 are all unidirectional gauges and are arranged along the length direction of the side line; Strain gauges are pasted on the front and rear surfaces of the slider 200 as Figure 8 shown. Some of the measuring points on the front surface are: H1 - H5, and some of the measuring points on the rear surface are: H9 - H13; Strain gauges are pasted on the left and right surfaces of the slider 200 as Figure 9 shown. Some of the measuring points on the left surface are: H6 - H8, and some of the measuring points on the right surface are: H14 - H16. The measuring points in the H series are all unidirectional gauges and are arranged along the length direction of the side line.

[0084] Strain gauges are pasted on the front and rear side surfaces of the base 700 as Figure 10 shown. The measuring points J1 - J10, D1 - D15 are all unidirectional gauges. The measuring points D1 - D15 are arranged along the length direction of the side line, and the measuring points J1 - J10 are arranged vertically along the rib direction.

[0085] Strain gauges are pasted on the front and rear side surfaces of the workbench 600 as Figure 11 shown. The measuring points T1 - T14 are all unidirectional gauges. T1 - T7 are pasted on the front surface of the workbench 600, and T8 - T14 are pasted on the rear surface of the workbench 600, and are arranged along the length direction of the side line.

[0086] Strain gauges are pasted at each measuring point of the left front column 100, right front column 500, left rear column 800 and right rear column 900. The front and rear surfaces of the left front column 100 have several measuring points as Figure 12As shown, the measuring points on the front surface are: Z1, Z2, Z5, Z6, Z9 and Z10, and the measuring points on the rear surface are: Z3, Z4, Z6, Z8, Z11 and Z12; there are several measuring points on the front and rear surfaces of the right front column 500 as Figure 13 shown, the measuring points on the front surface are: Z13, Z14, Z17, Z18, Z21 and Z22, and the measuring points on the rear surface are: Z15, Z16, Z19, Z20, Z23 and Z24; there are several measuring points on the front and rear surfaces of the left rear column 800 as Figure 14 shown, the measuring points on the front surface are: Z25, Z26, Z29, Z30, Z33 and Z34, and the measuring points on the rear surface are: Z26, Z28, Z30, Z32, Z34 and Z36; there are several measuring points on the front and rear surfaces of the right rear column 900 as Figure 15 shown, the measuring points on the front surface are: Z37, Z39, Z41, Z42, Z45 and Z46, and the measuring points on the rear surface are: Z39, Z40, Z42, Z44, Z46 and Z48; all the Z-series measuring points are single-sided gauges, and the gauges are arranged along the length direction of the column side line.

[0087] The single-sided gauge and the double-sided gauge correspond to 1 and 2 strain data respectively. The stress calculation process is as follows:

[0088] For the single-sided strain gauge, the stress-strain formula for the single-sided stress state: σ = Eε;

[0089] For the double-sided strain gauge, there are two single-sided gauges in one double-sided strain gauge, which are distributed in the 0° and 90° directions, as Figure 16 shown, the stress-strain formula for the double-sided strain gauge:

[0090]

[0091]

[0092] Taking σ x , σ y and 0 as the three principal stresses respectively, and arranging them in the order of σ1 > σ2 > σ3;

[0093] Calculating the equivalent stress of this measuring point according to the fourth strength theory:

[0094]

[0095] For the weld positions such as the cross beam 300 and the base 700, double-sided gauges are arranged at 45° at the weld positions. According to the calculation formula:

[0096] where σ1 = τ, σ2 = 0, σ3 = -τ, and the strains measured by the resistance strain gauges in ε EL1 and ε ER1 are:

[0097]

[0098]

[0099]

[0100]

[0101] Then there are:

[0102]

[0103] The various parameters of the fuselage are shown in Table 3:

[0104] Table 3 Basic Parameters of the Fuselage

[0105] Crossbeam Upper slider Workbench Base Column Spindle sleeve Elastic modulus GPa 206 206 210 206 206 212 Poisson's ratio 0.3 0.3 0.29 0.3 0.3 0.291

[0106] When testing the dynamic stress, the loading tonnage is 1600t, and the measuring point positions are at the places where the static stress is relatively large and the possible stress is relatively large among various parts of the fuselage, specifically including all measuring points of T5, L8, H3, H1, HU3, HU7, K5, F1, HD1 to HD8, and Z1. The sampling frequency selected for this dynamic stress test is 51.2Hz, the voltage range is ±5000mV, and the strain amplifier settings are: bridge voltage 2V, low-pass 100Hz, and gain 500. The voltage value corresponding to the measuring point is obtained by selecting the peak value in the waveform diagram. The strain value corresponding to the measuring point is obtained from the numerical value of the dynamic stress calibration above, and then the stress value of each measuring point is obtained through the stress calculation formula, as shown in Table 4.

[0107] Table 4 Strain and Stress of Each Measuring Point under Dynamic Loading

[0108]

[0109] The signal schematic diagram of the measuring point (specifically corresponding to the measuring point Z1) when measuring the dynamic stress by dynamic loading on the column is shown in Figure 17; the signal schematic diagram of the measuring point (specifically corresponding to the measuring point H3) when measuring the dynamic stress by dynamic loading on the slider 200 is as Figure 18 shown; the signal schematic diagram of the measuring point (specifically corresponding to the measuring point T5) when measuring the dynamic stress by dynamic loading on the workbench 600 is as Figure 19As shown, it can be seen from the above three waveform diagrams that during the stamping process, after the stamping goes down and then returns upward, the dynamic stresses on the column, slider 200, and workbench 600 do not quickly return to zero. The dynamic stresses of each component of the fuselage include not only the stamping force but also the inertial force, that is, the dynamic stress is jointly affected by the stamping force and the inertial force. The above dynamic load phenomenon was accidentally discovered through dynamic tests. By precisely measuring the dynamic stress, the parameters of the simulation model are corrected to improve the accuracy of the finite element simulation analysis. Then, according to the simulation results, the structure of the press is optimized in the finite element software, and the simulation is repeated until the optimal press structure is obtained, ensuring the designed dynamic accuracy index and improving the stamping accuracy of the press. It can be applied to the design work of large presses, especially suitable for the design work of press structures with a dynamic loading tonnage above 1000t.

[0110] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A structural design method for a large press, characterized in that: It includes the following steps: Roughly design the press; Test and measure the stiffness and strength of the slider (200), columns, and workbench (600) in the press; Conduct a simulation analysis of the press model and the workpiece forming process, compare and analyze with the experimental results, and adjust the simulation model according to the experimental results and the simulation effect of workpiece forming; Conduct topology optimization on the fuselage based on dynamic loads to obtain the optimized fuselage model; The test steps are as follows: Attach resistance strain gauges to the workbench (600), slider (200), columns, and crossbeam (300) respectively; Arrange displacement sensors on the crossbeam (300), workbench (600), and slider (200); Place several simulated hydraulic cylinders on the workbench (600); Start the press to conduct dynamic stress testing on the simulated hydraulic cylinders during stamping. The strain gauge collects the dynamic stress of each measuring point, and the displacement sensor collects the dynamic displacement of each measuring point; Through the dynamic stress testing of the press, it is obtained that the dynamic stress changes with time. The entire fuselage is subjected to the combined action of the punching force and inertial force during stamping. Take the maximum value of the dynamic stress and compare it with the finite element analysis result, and adjust the simulation model according to the maximum value of the dynamic stress; Before the dynamic stress testing, conduct static stress testing on the workpiece. Specifically: Press the slider (200) on the workpiece, gradually load the press, and each acquisition point is acquired 3 times during the loading process. Finally, take the average value of the 3 times as the strain value of each acquisition point; Calculate the equivalent stress of each acquisition point using the fourth strength theory; The displacement sensor collects the static displacement of each measuring point; During the dynamic stress testing, take the location with relatively large static stress in each part of the fuselage as the measuring point of the dynamic stress. Obtain the calibration value of the corresponding channel through the strain amplifier, calculate the dynamic strain of each measuring point, and obtain the stress value of each measuring point.

2. The structural design method of a large press according to claim 1, characterized in that: The calculation formula for the dynamic strain of the measuring point is: ； Among them, the waveform peak value is the peak value of the resistance signal wave generated by the resistance strain gauge collected during the dynamic stress testing.

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