The COSMOS finite element software was used to perform finite element analysis and calculation on the newly developed body of the toggle-type CNC punch press. The deformation and stress distribution of the fuselage under the nominal force were studied, and the main components of the fuselage structure were analyzed to the fuselage. The effect of stress and strain. According to the analysis results, the fuselage structure was optimized and designed to further reduce the weight of the fuselage, reduce the production cost, and improve the product's competitiveness.
1 Introduction
CNC turret punch press is a forging equipment that uses CNC technology to process sheet metal. Compared with general punch press, it contains an efficient CNC system and stamping die library. Through NC programming, it can realize rapid movement and positioning of the sheet material. It only needs to install one die to complete tens or even hundreds of blanking on the workpiece. Stamping processes such as shallow drawing, embossing, and stamping have high efficiency, good flexibility, and high accuracy. The mechanical drive numerical control turret punch press generally adopts a crank-slider mechanism. Although it has the characteristics of rapid return and force amplification, it is difficult to obtain an ideal working stroke curve due to the limitation of the mechanical structure, and the slider speed is not easy to change. The number of trips is low and power consumption is high. Although the hydraulic drive CNC turret punch can control the stroke and punching frequency of the slider well, it can control the size of the punching pressure according to the stamping plate and blanking parts. However, the hydraulic press punch also has the idle and return speeds, and the production is slow. Low efficiency, large motor power required, leaks, and other defects. The transmission mechanism of the toggle type CNC turret punch press is essentially composed of different types of double crank slider mechanisms, with a small crank radius, low power consumption, large working stroke, high return speed, and low and uniform at high frequencies. The process speed can also reduce vibration, reduce noise to 75dB(A), and reduce 10-20dB(A) compared to mechanical presses and hydraulic presses. Because of the reduced impact, the tool life can be increased by more than 3 times.
The midplane of the CNC turret punch press is one of the most critical components to bear all the work load. Therefore, the accuracy of the airframe punching machine plays a decisive role. Especially its stiffness, the design should focus on considerations, because the general punch is often not due to lack of strength and damage, but due to fuselage deformation affect the work of the punch. The stiffness of the fuselage not only affects the performance and service life of the press, but also directly affects the life of the mold on the machine tool and the machining accuracy of the formed parts, and even affects the smooth completion of the production. In addition, the numerical control turret punch punch throat depth is larger than the general punch press, and the body stiffness is more difficult to guarantee. Therefore, we use the finite element method to analyze the force of the fuselage, and reasonably design the fuselage structure so that the fuselage has enough rigidity to ensure the precision of the press and improve the product performance.
2 basic structure of the fuselage
The traditional numerical control turret punch press body is divided into open and closed type. The open type airframe has openings in all three directions, so it is easy to access the mold. It is convenient to install and remove the mold, and it can be operated both in the front, rear, and left and right directions. It is extremely convenient for operators, and it also has the advantages of simple structure, light weight, small footprint, and relatively low cost. For the working characteristics of the open type CNC turret punch press and reference to the related product structure, the fuselage will adopt a plate frame welded structure. After analyzing the welding processability of the fuselage structure and the mounting space requirements of the press parts, the basic structure of the preliminary design of the fuselage is shown in Fig. 1. The width of the fuselage is 350mm, the height is 2200mm, the throat depth is 1270mm, and the throat height is 575mm. Open structure welded by steel plate.
Figure 1 Overall structure of the bed
3 The establishment of a finite element model
COSMOS is a powerful set of finite element analysis software introduced by SRAC. The traditional method is to disassemble the parts when analyzing the assembly. Then one by one to deal with separately, time-consuming and labor-intensive, and there is the disadvantage of inaccurate calculation results. COSMOS offers complex assembly analysis of multiple fields/multiple components. This greatly simplifies the engineer's work. Making the analysis better simulates the real situation and the result is more accurate. At the same time, COSMOS uses FFE (Fast Finite Element) technology to greatly reduce the time-consuming engineering analysis time. The machine tool table has little effect on the stiffness and strength of the entire machine tool. Therefore, when building the finite element model, the work table and its All accessories are omitted. The finite element model established in COSMOS is shown in Fig. 2. The tetrahedral mesh is used for the overall division. The nominal force of 300kN acts on the work table and the crank mounting surface directly below the bearing hole, respectively, at the six anchor bolts. Three-direction restraints are applied and the steel plate is assumed to be ideally welded.
Figure 2 Bed Finite Element Model
4 Static analysis
Figure 3 and Figure 4 are the Von Mises stress cloud diagram of the static analysis of the fuselage and the overall deformation diagram of the fuselage (magnified 300 times).
From the figure, we can see that there are local high stress areas in the installation position of the toggle mechanism and servo motor, and the stress is 65MPa and 64MPa. At the same time, the four corners of the fuselage at the fuselage have obvious stress concentration, and the upper end of the throat is round. The angular stress is 52.7MPa, the fillet fillet stress at the lower end of the throat is 55MPa, and the minimum safety factor of the fuselage is 3.4. Obviously, the strength index will not become a difficult point in the design of the fuselage. After the fuselage is loaded, the maximum displacement of the overall deformation is 1.028mm. The maximum displacement occurs at the top of the beam on the fuselage and the stress and deformation distribution of the entire fuselage is available: In addition to the stress concentration in a few areas, the stress value is low. The fuselage strength meets the requirements; however, the displacement and the rotation angle of the height direction of the beam on the fuselage are relatively large, which has a significant impact on the accuracy of the punch press. Therefore, it is necessary to improve the structure of the fuselage or connect the thickness of the steel plate to improve the fuselage. Stiffness. According to the stress cloud diagram of the fuselage, the stress in most areas of the fuselage is very small, and the thickness of the side plates can be properly reduced. Considering changes in the rigidity of the fuselage, the reinforcing plate can be welded at the throat position. The modified fuselage structure is shown in Figure 5 .
Fig. 5 Improved bed structure
5 body optimization design
To optimize the design of the fuselage, we must first study the influence of the thickness of each connecting plate that constitutes the fuselage structure on the performance parameters of the fuselage.
5.1 Effect of Side Plate Thickness on Strength and Stiffness of the Airframe
After calculation, the weight of the two side plates accounts for 54% of the total weight of the fuselage, and the change in the thickness of the side plates will cause a large change in the total weight of the fuselage. At the same time, the side plates bear most of the stress, and the strength and stiffness of the whole machine are mainly determined by the thickness of the side plates. Here, the main consideration is the change in fuselage deformation with the thickness of the side plate.
From Fig. 6 (when the thickness of the reinforcing plate is 40mm), it can be seen that the stiffness of the fuselage varies greatly with the variation of the thickness of the side plate. When the thickness of the side plate changes from 20mm to 60mm, the maximum deformation of the fuselage decreases from 1.512mm. It is 0.739mm.
Figure 6 The maximum deformation of the fuselage with the thickness of the side plate changes
5.2 Reinforce the effect of the board on the fuselage stiffness
The same method was used to analyze the effect of stiffeners on the stiffness of the fuselage. From Figure 7 (thickness of the side plate is 40mm) we can see that the stiffness of the fuselage varies with the thickness of the reinforcing plate. When the thickness of the reinforcing plate changes from 20mm to 60mm, the maximum deformation of the fuselage is only reduced by 1.085. To 0.914.
5.3 Influence of the baffle on the stiffness of the fuselage
As can be seen from Fig. 8, the thickness change of the baffle plate on the throat has little effect on the stiffness of the fuselage and can be neglected. However, considering that other accessories are to be installed on the baffle plate, the plate thickness can be minimized to save the plate material.
5.4 Body Optimization Design
The main components that make up the press body include side plates, stiffener plates, throat columns, throat flaps, throat flaps, punch columns, work tables, and some other baffles. In order to simplify the optimization process, the selected design variables are mainly the thickness of the various parts of the fuselage. Here, the thickness of the side plate, the reinforcement plate, the throat column, the upper throat plate, the lower throat plate, and the bottom plate are selected as the design. The variable, with the total volume of the fuselage as the final optimization goal, takes the maximum Von Mises stress of the fuselage and the maximum deformation of the fuselage as constraints.
After 51 iterations in COSMOS, the relationship between volume and number of iterations in the calculation process is shown in Figure 9, from which a set of optimal results is selected, and the optimized dimensions are rounded and unified as the final optimization result. The thickness of the steel plate before and after optimization is shown in Table 1.
After optimization, the maximum deformation of the fuselage was reduced from 1.028 to 0.942. The stiffness of the fuselage was slightly higher than before, and the total weight of the fuselage was reduced by 468 kg. Compared with the original, steel was saved by 6%, which reduced the production cost and further improved the product's Competitiveness.
6 Conclusion
Using the finite element method, the force analysis and structural optimization of the press body of a new type of toggle CNC turret punch press can accurately calculate the stress and strain of various parts of the fuselage. Under the premise of ensuring the strength and rigidity of the fuselage, the welding structure and the thickness of the welded steel plate of the most optimized body are provided. The design of the fuselage with the best performance and the lowest material consumption and manufacturing costs, in order to obtain the best economic and social benefits.
The structure feature of the Earth Wire Clamp:
1. Puncture structure, to insure the puncture pressure, and it's easy to fix.
2. Pressurized structure, corrosion protection, and have a longevity of service.
3. Contact resistance is small, and the temperature of cord grip is low.
4. It's connected with different pathway lead, and it's useful.
5. Insulating property is wonderful.
If you have any questions, please contact with us directly.
Our company is solemnly committed to the majority of customers: reasonable price, short production cycle, considerate service. We look forward to cooperating with you.
Earth Wire Clamp
Earth Wire Clamp,Jdl Earth Wire Clamp,Jbc Earth Wire Clamp,Puncture Grounding Wire Clamp
Shandong Vantage International Trade Co., Ltd. , https://www.steelplate.be