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0 Introduction Bevel gear precision forging technology refers to the precision die forging process in which gear teeth are directly forged when the gear is forged and the tooth surface is no longer machined. Bevel gears are widely used in differentials for automobiles, tractors, motorcycles, tanks, etc. They have a wide range of applications and demand. Production of bevel gears using traditional mechanical cutting methods is slow, inefficient, and has poor accuracy. The hot forging forming technology of bevel gears has basically matured, but in the aspect of cold forging and closed forming technology, it needs to be further improved and improved. Forming parts using cold forging method can save raw materials, improve the mechanical properties of parts, and can It is a high-yield, high-quality, low-consumption process technology that achieves the desired dimensional accuracy and surface roughness. The economic benefits are considerable. However, there are also problems such as large deformation resistance and high requirements for molds and equipment. Therefore, it is necessary to design and analyze the cold precision forging process and mold of the bevel gear.
The 3D CAD system has better modeling tools and can realize design methods such as "from top to bottom" and "from bottom to top" to realize complex design processes such as assembly and make the design more in line with the actual design process; the three-dimensional modeling system can be conveniently Connected with the CAE system for simulation analysis; can provide the information required for CNC machining and integrate CAD/CAE/CAPP/CAM. Based on these advantages of three-dimensional CAD system, this article uses SolidWorks three-dimensional design software to complete the design of bevel gear and its mold.
l Bevel gear precision forging process Cold precision forging is a net forming process developed rapidly with the automobile industry. The precision forging bevel gear has continuous metal flow lines and dense tissues distributed along the tooth profile. The strength of the gear teeth, the wear resistance of the tooth surface, the heat treatment deformation amount and the meshing noise are all superior to those of the cutting gear. The gear material is medium and high strength alloy steel 20Cr, which has high strength in the supply state, large deformation resistance, poor plasticity, work hardening, and difficulty in cold forging forming with a large amount of deformation. However, if the blank is fully softened and annealed, the deformation resistance and the plasticity index of the material can be reduced. The precision forged bevel gears have improved strength and bending fatigue life, reduced heat treatment distortion, and reduced production costs. Based on the above analysis, it was decided to adopt a cold forging forming process. The process is as follows: blanking-annealed leaf cold forging, a finishing, inspection, storage. Prior to cold forging, the blanks should be softened and annealed between processes. Phosphating should be performed before cold forging.
2 Mould Design 2.1 Forgings Gear forgings are designed based on the bevel gear parts drawing and the basic requirements of the cold die forging process. The position of the parting surface is selected at the largest outer diameter of the part. Under the premise of ensuring effective tooth length, the large end of the bevel gear leaves an excessive fillet formed by the cold forging forming process, as shown in FIG. 1 .
The mold cavity of the precision forging bevel gear is a curved surface and the shape is relatively complex. In order to quickly and accurately obtain a high-quality curved surface shape, a three-dimensional modeling software SolidWorks is used to complete the geometric model design of the mold and the blank. Because the bevel gear's theoretical tooth profile curve is a spherical involute, it cannot be expanded into a plane, which brings great difficulties to the three-dimensional design of the bevel gear. In this paper, starting from the theory of back cone, combined with the involute equations and modeling commands in the drawing software, the true three-dimensional shape of the bevel gear is achieved to the maximum. Figure 2 shows the three-dimensional shape of the bevel gear parts. Fig. 3 shows the bevel gear forming die designed by using commands such as parting surface and parting line in SolidWorks software, and prepares for the numerical simulation analysis of the bevel gear process.
2.2 Mold Structure Design The working conditions of the bevel gear precision forging die are extremely harsh, and therefore put forward higher requirements on the precision, strength, rigidity and life of the die. The assembly drawing of the mold is shown in Figure 4, and its working process is as follows. It is used for the closed forging of workpieces on ordinary hydraulic presses. Place blanks during work
In the cavity of the lower die 13, after the blank is placed, the upper die 3 goes down; when the upper die 3 comes into contact with the blank, the contraction and extrusion begins; with the continued depression of the upper die 3, the stress ring 10 is under pressure. When the lower spring is squeezed and moved downwards, the billet enters the cavity of the closed state, the contraction is completed, and the extrusion molding phase begins; the upper die 3 continues to move down until the specified stroke is reached. After the upper die returns, the lower die 13 and the stress ring 10 return to the initial state under the action of the spring 8 . The formed bevel gear forgings are demoulded under the action of the upper ejector rod 19, and the forgings are removed. At this point, the bevel gear precision forging forming process is completed.
The tooth-shaped die is the most critical part of precision forging of bevel gears, and its accuracy determines the accuracy of the bevel gear forgings. The strength and life of the tooth profile die must not only be considered from the materials used, but must be ensured from the structural design of the die. In order to increase the strength of the toothed die, a modular structure is used. The floating upper mold core and the floating lower mold sleeve structure are used to deform the forgings in the closed annular mold cavity, the forgings have no flash, and the radial dimensional accuracy is high. Since the forgings have no flash, the horizontal projected area (forged area) is small, the required forging force is small, and the press tonnage is reduced. Due to the use of a floating mold structure, the concave cavity formed by the floating mold is deeper, ensuring accurate orientation of the upper and lower molds. This mold utilizes a spring for blanking and closed die forging.
3 Precision Forging Die 3D Model SolidWorks is a powerful CAD software. On the basis of completing the three-dimensional modeling of the product, dynamic visualization of the model can also be achieved, and the assembly process, disassembly process and operation process of the mold are simulated. The three-dimensional modeling of the precision forging die of the bevel gear is shown in Fig. 5. Through the interference check and the movement simulation of the bevel gear die, problems occurred in the design process were discovered early, and related parts were improved. Finally, 2D engineering drawings of assemblies and parts are generated.
4 Conclusion Production of gears using precision forging technology can not only reduce raw material and energy consumption, reduce manufacturing costs, but also improve the mechanical properties of gears. According to the bevel gear precision forging process, the reasonable shape of the forgings is designed. SolidWorks three-dimensional design software was used to complete the 3D solid modeling of bevel gear parts and precision forging dies. Through simulating the movement process of the dies, design problems can be discovered early, which is helpful to quickly find problems and improve structural design, thereby realizing the rapid development of precision forging dies. The design lays the foundation for the numerical simulation of precision forging processes.
This classification mainly includes the aluminum or zinc alloy die casting Chassis parts using in Agriculture area.
In the die casting process,higher specific pressure is required, so that higher filling speed can be obtained.which is beneficial for alloy to overcome mold filling resistance.and effectively fill each part of the cavity.The Casting General Tolerance is Grade GB-CT4.
Process Technology: High pressure die casting, Cold Chamber
Product Dimensions: Customized
Casting General Tolerance: Grade GB-CT4
Flow Processes: Die casting, Degating to remove the residual of the gate, Polishing and Deburring to remove the burrs, Polishing to remove the parting line, flash,CNC Turning, Cleaning, Packaging, Storaging, Shipping
Control Measure: Incoming Material Test, First Article inspection, Routing inspection, Final item inspection, and Outgoing quality control
Inspection Equipment: CMM, Caliper, Plug Gage, Screw Gauge
Application: Machinery Parts
Certificate: IATF16949:2016,ISO14001:2015,ISO45001:2018
Lead Time: 30-35 days
Trade Term: FOB Ningbo
Casting Agricultural Chassis Parts,Die Casting Agricultural Chassis Parts,Aluminum Casting Agricultural Chassis Parts
NINGBO ZHENHAI BOLANG METAL PRODUCTS FACTORY , https://www.casting-part.com