Meshing: Since the bed is a bilaterally symmetrical structure, the left and right main side plates are welded together by the ribs perpendicular thereto, and the structure can be illustrated by the flat 3D model diagram. N2, N22, etc. are a main side panel mesh node number. The number in parentheses, such as (N125) (N145), etc. is the number of the other main side plate node; mechanical manufacturing and research Wang Baoling, etc. 300kN CNC die turret existing design 3D grid diagram constitutes the board of the bed All are thin steel plates. According to the nature of the thin shell unit, as long as the side length of the control unit is not less than 5 times the thickness of the plate, the shell element can be used to simplify the model. The three-node and four-node shell elements are used for meshing. The two main side panel units are uniformly divided, and the mesh is encrypted at the portion where the stress is concentrated (the two corners of the throat and the bearing hole). The ribs are individually meshed and connected by the node and the main board; c) the load is simplified: when the press is working, the reaction force of the punch acts on the bearing housing hole of the bed through the rotating shaft, the bearing and the bearing seat. . The force exerted by the punch on the workpiece is transmitted to the bed through the work surface. According to the actual measurement, the maximum load on the bed is 1.5 times of the engineering pressure. A load of 450 kN (300 kN 1.5) was applied to the stiffness analysis of the bed.

The finite element analysis results of the bed a) Strength analysis: When loading 450kN, the maximum principal stress is 91.72Mpa, the reference. The maximum principal stress occurs at node 22 (throat fillet), the reference, the key point stress is listed in each node position reference; the original design stress coloring map original design stress table node number principal stress / MPa node number main stiffness analysis : When 450kN is loaded, the maximum deformation is 2.1310-1cm.

Before and after the original design deformation, the bed is an open structure. As can be seen, the maximum deformation occurs at node 80 and node 203. The focus of our attention is on the deformation of the shaft hole relative to the work surface, so it is still necessary to analyze the key point displacement. The key node displacement is given by post processing.

Since the bed is a left-right symmetric structure, only the node 79 is analyzed. The position of the node 79 corresponding to the table pad is the midpoint of the node 39 and the node 54. According to the displacement at the midpoint of 39 and 54 is obtained: /2 = -4.419510-3 The deformation of the node 79 relative to the table is 0.181-(-4.419510-3) 0.1854 cm3. It is preferable to reduce the throat size or increase the bed. The rigidity is a key factor in increasing the stiffness of the bed, which is not desirable at the expense of reducing the throat size at the expense of product performance. If you simply increase the thickness of the motherboard, the increase in stiffness will also bring about an increase in cost. Therefore, the preferred design goal is to reduce the bed quality and increase the rigidity of the bed without reducing the strength of the bed.

According to the actual structure and finite element analysis of the 300kN CNC die turret pressure machine body. We made the following design changes. For reference, the two main side plates of the U-shaped frame on the left side are each thinned by 5 mm, the reduced mass is 13.8% of the total mass of the bed, and the main side plate of the bed is thickened in the B box area in the lower right corner. 3mm, the added mass is about 112% of the total mass of the bed, and the total mass is reduced by 2.6%. The other structure of the bed remains unchanged.

After improving the design of the bed, the stress field and the displacement field of the bed are improved. The deformation of the key point (the upper edge of the bearing hole) relative to the work surface is calculated by the post-processing file: 0.1489 cm FEA. It is known that the stress is reduced from the original design of 9172 MPa to 87.12 MPa. It can be seen that the maximum deformation of the bed is reduced from 0.213 mm to 0.163 mm in the original design. The key point deformation is reduced from 0.1854 cm to 0.1489 cm. 197%. At the same time, the quality of the bed is reduced by 2.6%.

Conclusion Using the finite element method to analyze the strength and stiffness of the 300kN CNC die turret pressure machine body, the stress distribution and bearing of the bed corner deformation can be obtained after the traditional simple supported beam method can not be calculated. Deformation at the seat hole. The result is more accurate and reliable than the traditional method. The preferred design of the bed by means of the finite element method has achieved satisfactory results. It lays a solid foundation for the structural design and optimization of the bed in the future.

(Finish)

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