Stamping Closed-Loop Control System and Method Based on Stress and Roughness Levels

Abstract

This invention discloses a stamping closed-loop control system and method based on stress and roughness levels, belonging to the field of stamping closed-loop control technology. It includes a lower die base, a laser surface roughness measuring instrument in the middle of the lower die base, a stripper plate at the bottom of the lower die base, a concave die in the middle of the stripper plate, a groove on the concave die, a strain gauge placed in the groove, a static strain analyzer at the top of the stripper plate, an upper die base connected to the top of the stripper plate via a support rod, a punch connected to the middle of the upper die base via an insulating sleeve, and a pressure servo motor at the top of the punch. This invention, employing the aforementioned stamping closed-loop control system and method based on stress and roughness levels, can achieve closed-loop control of parameters such as stress and roughness of sheet metal during multi-physics-assisted stamping processes, while also possessing advantages such as high control accuracy and low cost.

Description

Technical Field

[0001] This invention relates to the field of stamping closed-loop control technology, and in particular to a stamping closed-loop control system and method based on stress and roughness levels. Background Technology

[0002] With the continuous improvement of production demands, multi-energy field assisted stamping processes such as hot forming, electric assisted forming, and ultrasonic assisted forming have emerged. These new forming methods have greatly improved the stamping accuracy of difficult-to-deform materials. However, the current multi-energy field assisted stamping process uses an open-loop control method. The multi-energy field assisted stamping process based on open-loop control requires a lengthy optimization process to obtain suitable physical field parameters.

[0003] Furthermore, this open-loop control method does not allow for complete optimization and generally requires the use of attenuation control methods to achieve complete optimization, which increases the optimization and adjustment time. Therefore, the open-loop control method is not applicable to industrial production. In view of this, the present invention provides a closed-loop control system for stamping multiphysics loading parameters based on stress and roughness level adjustment. Summary of the Invention

[0004] The purpose of this invention is to provide a stamping closed-loop control system and method based on stress and roughness levels, which can realize closed-loop control of parameters such as stress and roughness of sheet metal during multi-physics field assisted stamping process, and has the advantages of high control accuracy and low cost.

[0005] To achieve the above objectives, the present invention provides a stamping closed-loop control system based on stress and roughness levels, including a lower die base, a laser surface roughness measuring instrument in the middle of the lower die base, a stripper plate at the bottom of the lower die base, a concave die in the middle of the stripper plate, a groove on the concave die, a strain gauge placed in the groove, a static strain analyzer at the top of the stripper plate, an upper die base connected to the top of the stripper plate by a support rod, a punch connected to the middle of the upper die base by an insulating sleeve, and a pressure servo motor at the top of the punch.

[0006] Preferably, the pressure servo is connected to a computer to obtain pressure data.

[0007] Preferably, the critical area in the stamping process is first obtained through finite element analysis. The strain gauge is connected to a static strain analyzer to measure the strain in the critical area. The static strain analyzer is connected to a computer to obtain stress data at different times.

[0008] Preferably, a pressure plate is provided between the upper mold base and the unloading plate, and the pressure plate is connected to a constant current power supply.

[0009] Preferably, an ultrasonic transducer is installed on the right side of the unloading plate. The ultrasonic transducer is connected to an ultrasonic generator via an ultrasonic amplitude transformer for loading the ultrasonic field. The ultrasonic generator and the constant current power supply are both connected to a computer.

[0010] This invention provides a method for a stamping closed-loop control system based on stress level, comprising the following steps:

[0011] S101. Install the mold, strain gauge and plate in place, then connect the pressure servo machine, static strain analyzer and computer, and then connect the constant current power supply to the edge clamp.

[0012] S102. Start the pressure servo machine. At the same time, the computer receives the current strain and pressure data through the static strain analyzer and the pressure servo machine to calculate the stress value in the critical area.

[0013] S103. Compare the real-time collected stress values ​​of the hazardous area with the set maximum stress value;

[0014] S104. If the current stress value is greater than the set maximum stress value, then start the constant power supply to apply a current field to the sheet metal.

[0015] If the current stress value is detected to be no greater than the target stress value, the current loading is stopped.

[0016] The present invention also provides a method for a stamping closed-loop control system based on roughness level, comprising the following steps:

[0017] S201. Install the stamping equipment onto the pressure servo machine, install a laser surface roughness measuring device at the lower die base, connect an ultrasonic generator at the unloading plate, and connect the ultrasonic generator to the computer.

[0018] S202. Start the pressure servo motor and the control system monitors the surface quality of the sheet material in real time through the laser surface roughness measuring instrument.

[0019] S203. Compare the current surface roughness with the set maximum roughness;

[0020] S204. If the roughness exceeds the set maximum roughness, an ultrasonic field is applied to the board material, and the surface quality of the board material is improved under the action of the ultrasonic field.

[0021] Stop loading the ultrasonic field when the monitored roughness is not greater than the target roughness value.

[0022] The present invention also provides a method for a stamping closed-loop control system based on stress and roughness levels, as described above, comprising the following steps:

[0023] S301. After installing the stamping module, strain gauge, static strain analyzer and laser surface roughness measuring instrument, connect the constant current power supply and ultrasonic generator to the edge clamping plate and the unloading plate respectively.

[0024] S302. Start the stamping device. The control system uses a pressure servo motor, pressure transformer analyzer and laser surface roughness measuring instrument to realize real-time monitoring of stress and surface roughness in the dangerous area.

[0025] S303. Compare the current stress level and surface roughness value with the set maximum stress value and roughness value;

[0026] S304. If either of the two indicators is greater than the set maximum value, the difference between the current value and the set value is calculated, and the difference is imported into the empirical formula obtained from the experiment to obtain various different current and ultrasonic parameters. The control system selects the appropriate field parameters and starts the constant current power supply and ultrasonic generator.

[0027] S305. After loading the current and ultrasonic parameters for a period of time, the stress level and roughness simultaneously meet the target values. Then, the current and ultrasonic field are disconnected, and the stress and roughness are monitored again.

[0028] Therefore, the present invention adopts the above-mentioned stamping closed-loop control system and method based on stress and roughness levels, realizing the industrialization of multi-physics field assisted forming process. While stabilizing and controlling process parameters such as stress and roughness during the forming process, it also ensures that the sheet metal does not overheat and melt under the action of current, saving energy and improving forming accuracy.

[0029] The surface quality of components produced by the closed-loop control system is controlled within a certain range, realizing the control of multi-physics field assisted forming parameters.

[0030] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a stamping closed-loop control system based on stress and roughness levels according to the present invention;

[0032] Figure 2 This is a flowchart of a closed-loop control method based on stress level according to the present invention;

[0033] Figure 3 This is a flowchart of a closed-loop control method based on roughness level according to the present invention;

[0034] Figure 4 This is a flowchart of a closed-loop control method based on stress and roughness levels according to the present invention.

[0035] Figure Labels

[0036] 1. Pressure servo motor; 2. Upper die base; 3. Static strain analyzer; 4. Computer; 5. Punch; 6. Pressure plate; 7. Stripper plate; 8. Ultrasonic transducer; 9. Ultrasonic amplitude transformer; 10. Ultrasonic generator; 11. Die; 12. Laser surface roughness measuring instrument; 13. Constant current power supply; 14. Lower die base; 15. Strain gauge; 16. Insulating sleeve; 17. Support rod. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0039] Example 1

[0040] This invention provides a stamping closed-loop control system and method based on stress and roughness levels. A schematic diagram of the control system is shown below. Figure 1 As shown, the device includes a lower die base 14, with a laser surface roughness measuring instrument 12 located in the middle of the lower die base 14 to realize real-time monitoring of the surface roughness of the parts during the stamping process. A stripper plate 7 is located at the bottom of the lower die base 14, with a die cavity 11 in the middle of the stripper plate 7. A groove is provided on the die cavity 11, and a strain gauge 15 is placed in the groove. A static strain analyzer 3 is located at the top of the stripper plate 7. The top of the stripper plate 7 is connected to an upper die base 2 via a support rod 17. A punch 5 is connected to the middle of the upper die base 2 via an insulating sleeve 16. A pressure servo motor 1 is located at the top of the punch 5.

[0041] First, the critical area in the stamping process is obtained through finite element analysis. Strain gauge 15 is connected to static strain analyzer 3 to measure the strain in the critical area. Static strain analyzer 3 is connected to computer 4 to obtain stress data at different times.

[0042] The pressure servo motor 1 is connected to the computer 4 to obtain pressure data. A groove of a certain depth and width is machined in the die 11 at the position corresponding to the danger zone.

[0043] A pressure plate 6 is provided between the upper mold base 2 and the unloading plate 7. The pressure plate 6 is connected to the constant current power supply 13 to realize the input of current.

[0044] An ultrasonic transducer 8 is installed on the right side of the unloading plate 7. The ultrasonic transducer 8 is connected to the ultrasonic generator 10 through the ultrasonic amplitude transformer 9 for loading the ultrasonic field. The ultrasonic generator 10 and the constant current power supply 13 are both connected to the computer 4 to realize closed-loop control of parameters such as stress and roughness.

[0045] This invention provides a method for a stamping closed-loop control system based on stress level, the flowchart of which is shown below. Figure 2 As shown, it includes the following steps:

[0046] S101. Install the stamping die on the pressure servo machine 1, and press and fix the sheet metal on the die with the pressing plate 6, and check whether the sheet metal is positioned correctly.

[0047] S102. A current field is introduced at the pressure plate 6, and the current amplitude is set by the power supply. The constant current power supply 13 is connected to the computer 4, and the control system uses the computer 4 to set the current amplitude and switch the power supply on and off.

[0048] S103. To monitor stress levels in real time, the pressure servo motor 1 and the static strain analyzer 3 are connected to the computer 4 to obtain the pressure applied by the press and the magnitude of the strain in the critical area during the stamping process. Then, the magnitude of the stress σ in the critical area is calculated. c ;

[0049] S104. Set the maximum stress value σ at point 4 on the computer. max and minimum stress value σ min The maximum and minimum stress values ​​should be set taking into account factors such as mold strength, sheet material properties, and sheet material melting point;

[0050] S105. Start the pressure servo machine 1 to begin stamping, and obtain the current stress level value through the computer 4.

[0051] S106, Set the current stress value σ c With the set maximum stress value σ max Compare;

[0052] S107, If the current stress value σ c Greater than the maximum stress value σ max The control system turns on the power, and current is input into the sheet metal. Under the action of the current, the flow stress gradually decreases.

[0053] When the monitored stress value σ c Less than or equal to the minimum stress value σ min When this happens, the control system disconnects the power supply and cuts off the current.

[0054] This invention also provides a method for a stamping closed-loop control system based on roughness level, the flowchart of which is shown below. Figure 3 As shown, it includes the following steps:

[0055] S201. Install the stamping molds, then fix the sheet metal between the molds and check whether the sheet metal is correctly positioned.

[0056] S202. The ultrasonic field can be introduced through the ultrasonic transducer 8 on the right side of the unloading plate 7, and the ultrasonic parameters can be set through the ultrasonic generator 10. The ultrasonic generator 10 is connected to the computer 4 to realize the control system's regulation and opening / closing of the ultrasonic parameters;

[0057] S203. Install a laser surface roughness measuring device 12 at the lower mold base 14 and connect the measuring device to the computer 4 to control the system to receive roughness data.

[0058] S204, Set the maximum roughness value Ra max and minimum roughness value Ra min The roughness value set depends on the component requirements;

[0059] S205. Start the pressure servo motor 1 to perform stamping. The control system obtains the current roughness value Ra through the laser surface roughness measuring instrument 12. c ;

[0060] S206, The control system will update the current roughness value Ra. c With the set maximum roughness value Ra max Compare;

[0061] S207, If the current roughness value Ra c Greater than the set maximum roughness value Ra max If the control system turns on the ultrasonic generator 10 to input ultrasonic waves into the sheet metal, it will reduce the surface quality of the sheet metal.

[0062] S208. As the ultrasonic field is applied, the current roughness value Ra... c It continues to decrease. When the roughness value Ra c The value is less than or equal to the minimum roughness value Ra min At that time, the control system disconnects the ultrasonic field.

[0063] This invention also provides a method for a stamping closed-loop control system based on stress and roughness levels, the flowchart of which is shown below. Figure 4 As shown, it includes the following steps:

[0064] S301. Complete the placement of the mold and sample, and install the static strain analyzer 3, strain gauge 15, and laser surface roughness measuring instrument 12 for analyzing and measuring stress and roughness values. Connect the static strain analyzer 3 and laser surface roughness measuring instrument 12 to the computer 4 to realize real-time monitoring of stress and roughness values ​​in the critical area by the control system;

[0065] S302, the current field and the ultrasonic field can be introduced through the pressure plate 6 and the unloading plate 7 respectively, and the parameters and opening and closing of the current and ultrasonic waves are controlled by the control system.

[0066] S303, Set the maximum roughness value Ra max Minimum roughness value Ra min Maximum stress value σ max Minimum stress value σ min These values ​​are set according to the properties of the sheet metal itself and the target forming quality;

[0067] S304. Start the pressure servo motor 1 to begin stamping. The control system obtains the current stress value σ through the pressure and strain data transmitted from the pressure servo motor 1 and the static strain analyzer 3. c Current roughness value Ra c The surface roughness is then measured using a laser surface roughness measuring instrument 12;

[0068] S305, Set the current stress value σ c and roughness value Ra c With respect to the set maximum stress value σ max and maximum roughness value Ra max If either of the two values ​​is greater than the set value, then the current stress value σ is calculated. c and roughness Ra c With the set minimum stress value σ min and minimum roughness Ra min The difference between them is denoted as Δσ and ΔRa;

[0069] S306. The control system will substitute the obtained Δσ and ΔRa into the empirical formulas Δσ=f(A,R,f,v) and ΔRa=f(A,R,f,v) obtained from the experiment, respectively, where A is the current amplitude, R is the sheet resistance, f is the ultrasonic frequency, and v is the ultrasonic wave velocity. The computer program will select appropriate current and ultrasonic parameters.

[0070] S307. The control system selects and sets appropriate field parameters, and starts the constant current power supply 13 and ultrasonic generator 10 to input electric and ultrasonic fields into the sheet metal.

[0071] S308. After being subjected to an electric current field and an ultrasonic field, both the stress level and roughness will reach the target values, i.e., σ. c Ra c Simultaneously decreased to σ min Ra min The control system then disconnects the ultrasonic field and the electric field.

[0072] Therefore, the present invention adopts the above-mentioned closed-loop control system and method for stamping based on stress and roughness levels, which can realize closed-loop control of parameters such as stress and roughness of sheet metal during multi-physics field assisted stamping process, and has the advantages of high control accuracy and low cost.

[0073] Finally, 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for a stamping closed-loop control system based on stress and roughness levels, characterized in that, The stamping closed-loop control system includes a lower die base, a laser surface roughness measuring instrument in the middle of the lower die base, a stripper plate at the top of the lower die base, a concave die in the middle of the stripper plate, a groove on the concave die, a strain gauge placed in the groove, a static strain analyzer at the top of the stripper plate, an upper die base connected to the top of the stripper plate via a support rod, a punch connected to the middle of the upper die base via an insulating sleeve, and a pressure servo motor at the top of the punch; the pressure servo motor is connected to a computer for obtaining pressure data. The critical area in the stamping process is obtained through finite element analysis. The strain gauge is connected to a static strain analyzer to measure the strain in the critical area. The static strain analyzer is connected to a computer to obtain stress data at different times. A pressure plate is provided between the upper mold base and the unloading plate, and the pressure plate is connected to a constant current power supply; an ultrasonic transducer is installed on the right side of the unloading plate, and the ultrasonic transducer is connected to an ultrasonic generator through an ultrasonic amplitude transformer for loading the ultrasonic field; the ultrasonic generator and the constant current power supply are both connected to a computer. The control method includes the following steps: S301. Complete the installation of the stamping die and the sample, and install the strain gauge, static strain analyzer and laser surface roughness measuring instrument. Then connect the constant current power supply and the ultrasonic generator to the edge plate and the stripper plate respectively. S302. Start the stamping device. The control system uses a pressure servo motor, pressure transformer analyzer and laser surface roughness measuring instrument to realize real-time monitoring of stress and surface roughness in the dangerous area. S303. Compare the current stress level and surface roughness value with the set maximum stress value and maximum roughness value; S304. If either of the two indicators is greater than the set maximum value, the current value is subtracted from the set minimum stress value and minimum roughness value respectively. The difference is then imported into the empirical formula obtained from the experiment to obtain various different current and ultrasonic parameters. The control system selects the appropriate field parameters and starts the constant current power supply and ultrasonic generator. S305. After loading the current and ultrasonic parameters for a period of time, the stress level and roughness simultaneously meet the target values. Then, the current and ultrasonic field are disconnected, and the stress and roughness are monitored again.

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