Preface
The application of CNC machine tool technology in various production fields of society has attracted wide attention from researchers in the industrial field. However, while the scale and speed of the CNC machine tool manufacturing industry continue to develop, there have also been low mechanical efficiency and reduced performance. Various problems. The CNC hydraulic bending machine is one of the most widely used CNC machine tools.
This article briefly introduces its concept and function, and then introduces the structure, and then conducts an in-depth study on the optimization design method of CNC hydraulic bending machine.
What is CNC hydraulic bending machine?
The CNC hydraulic bending machine is actually a double-cylinder upward-moving CNC hydraulic bending machine. It drives the return and extension of the left and right cylinders by means of the actions issued by each valve arranged in the servo proportional valve, and drives the lifting movement of the slider.
For the synchronization of the slider, the main application is full-closed-loop electro-hydraulic servo control technology. The grating rulers on both sides feedback the position signal of the slider itself to the CNC system. Then, the CNC system synchronously controls the opening size of the synchronization valve and controls the cylinder In the end, it can be adjusted automatically, and finally, the synchronous operation of the slider axis is realized, and it is always kept in parallel with the worktable.
Structural Analysis of CNC Hydraulic Bending Machine
Static analysis of fuselage structure
Using ANSYS finite element analysis method to simulate and analyze the overall displacement distribution of the CNC hydraulic press brake body, the displacement distribution in the X, Y, and Z directions, and the displacement distribution of the body throat, thereby calculating the amount of displacement distribution in the direction of 5 bending machines.
Through analysis, it is found that the deformation of the bending machine itself in the working process can basically meet the requirements of CNC accuracy, but in terms of the throat, due to the large stress at the lower position, and the maximum can reach 169MPa, it exceeds allowable stressth of the normal bending machine(160Mpa). In the actual work process, the part that is most prone to fatigue and fracture is also the throat of the bending machine. Therefore, this area at the throat should be optimized, and we should reduce the stress value appropriately to ensure the strength of the structure.
Static analysis of slider structure
The ANSYS finite element analysis method is used to simulate and analyze the displacement distribution of the slider of the CNC hydraulic bending machine under three different load conditions. The three conditions are: the full length of the slider is loaded, the middle load and the eccentric load.
The research results show that when the sliding block is under full-length load, the type variable that occurs is the smallest; when it is under intermediate load, the type variable that occurs is the largest.
Therefore, in the actual application process, the load on the middle of the slider of the bending machine should be avoided as much as possible, and the eccentric load condition should be the main as possible. For general CNC hydraulic press brakes, the loading condition of the slider constraint can be understood through stiffness analysis, while the work accuracy of the slider of the press brake produced by the normal slider stiffness can only reach level B, which cannot be satisfied. For lean production of products, need optimizing the structure of this part of the slider to improve the lean level of the product.
Static analysis of workbench
Using the finite element analysis software ANSYS, carry out the force analysis of the deformation field of the CNC hydraulic bending machine table under the full-length load, the intermediate load and the eccentric load. When the full-length load is pumped, the performance variable generated by the workbench is the smallest; when the intermediate load is subjected, the type variable is the largest.
However, according to the analysis results of ANSYS software, the deformation of the worktable is greater than that of the slider under the same working conditions. The reason for this phenomenon is that there are three rectangular small holes in the middle of the worktable, which are mainly used to compensate the installation of the oil cylinder, in order to achieve the purpose of compensating the deformation of the slider.
Optimal design of CNC Hydraulic Bending Machine
Optimal design of shape and size
The optimization principle of the hydraulic bending machine fuselage is: on the condition of the change of the fuselage structure, use the finite element separation software ANSYS to calculate the maximum vertical deformation of the fuselage and the maximum pressure at the throat, ensure that it is in the original structure and the overall constraint range of deformation and allowable stress, the main purpose is to reduce the weight of the fuselage.
Therefore, in the design of the bending machine, the throat fillet radius should be increased as much as possible when the throat depth meets the relevant standards to achieve the purpose of reducing the maximum stress of the throat.
Local strength optimization
When the CNC hydraulic bending machine is working, the throat breaks easily. Therefore, in order to ensure the bending accuracy of the machine and prolong the service life of the hydraulic bending machine, we must pay attention to optimized and improve this area. By adding C-shaped reinforcing ribs on the inner and outer sides of the side plate throat, so as to reduce the deformation of the body of the bending machine and the stress borne by the throat.
After compeleting the local strengthening work, we cauculate the deformation of the fuselage and the pressure on the throat twice, and then the maximum variable of the fuselage of the bending machine and the maximum pressure on the throat are changed with the width of the side plate of the bending machine. After improvement, it was found that although the maximum deformation and the maximum pressure of the fuselage and throat increased slightly with the increase of the width of the side plate, the general deformation of the fuselage and the general pressure of the throat both are significantly reduced, thus proving the feasibility of the optimization method.
Optimization of the position of the compensation cylinder of the worktable
Set the distance H between the middle compensation cylinder of the bending machine and the worktable surface (unit: mm, the same below), the distance between the three compensation cylinders is D, the compensation cylinders on both sides relative to the middle compensation cylinder in the vertical direction of the worktable The displacement is H1.
When optimizing：
- First, keep H unchanged, change the values of D and H1, analyze the overall deformation of the workbench, and determine the values of H, D, and H1 when the deformation curve of the workbench and the slider can fit well.
- Secondly, after this optimization, the maximum compensation amount of the cylinder position of the worktable is determined, so as to reduce the deformation of the worktable and improve the operational safety and efficiency of the CNC hydraulic bending machine.
Conclusion
This article briefly introduces the concept and application of CNC hydraulic bending machine. Based on the analysis of the general type of CNC hydraulic bending machine's fuselage structure, slider structure, and the related performance of the worktable,we optimizing the structure of the CNC hydraulic bending machine from the shape and size of the fuselage, the local strength and the position of the compensation cylinder of the worktable.
The research results show that the optimization method of the bending machine structure mentioned in this article can effectively reduce the deformation of the bending machine body and the pressure borne by the throat, and reduce the deformation of the table, and improve the work efficiency of CNC hydraulic bending machine in general.
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