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Experimental Study on Precision Forming of Gear Cold Extrusion Zeng Xianwen, Ren Xianyu, Li Da, Li Jiyun, Teng Hongchun (Department of Forging and Pressing, Jilin University of Technology, Changchun 130025, Jilin, China). Constrained diversion has many advantages in improving filling and other aspects, providing practical application for production. Feasibility basis.
The required precision forming gear parts The remaining 6.3 casts 1 set number 30 survey shape 202.25 2 extrusion forming test 2.1 process plan to determine the bookmark0 test using optomechanical gears (such as) as extrusions for cold extrusion precision forming test research, The material is LY12 hard aluminum. After the spur gear is extruded, its tooth shape is no longer mechanically machined, and the tooth shape should be filled well when squeezed. The height direction starts to be squeezed at the extrusion end, except that a proper mold angle is ensured on the die, and an overflow port is provided at the inner hole of the workpiece so that the intermediate metal flows to the overflow port at the final pressure. To achieve shaft shunting or hole shunting, while the external metal flows outward to ensure filling of the tooth profile. The constrained splitting is a certain constraint resistance to the metal flow, forcing the material to fill the tooth cavity to obtain the material under the cold state of the extrusion process. The deformation resistance is large, the fluidity is poor, and the corner is not easy to be filled, except in the extrusion process. In addition to the above measures, the LY12 hard aluminum billet (32.5x10) used was softened, heated to 420T for 4 hours, and the furnace was cooled to 150T: then air cooled. After annealing, the hardness was 50~60HBS. After softening, The material reduces deformation resistance, improves plasticity, and is easily extruded. The softened billet is then oxidized, saponified or oxidized and then lubricated with soybean oil to reduce friction between the flowing metal and the mold to fill the toothed cavity.
The conventional cutting process of the gear consumes more metal materials and man-hours, and the metal flow line is cut, and the tooth strength and fatigue life are reduced. In recent years, cold forging forming technology of toothed parts has been developed, and precision forged straight bevel gears have been widely used in automobiles, agricultural machinery, instruments and other industries. Gear cold extrusion precision forming has been highly valued at home and abroad. This advanced technology has the characteristics of material saving, high quality and high efficiency. Precision forming of cylindrical spur gears uses radial extrusion to form excessive pressure and is difficult to form. Usually, two-step forming methods of pre-forging and final forging are used. In this paper, the aluminum alloy LY12 hard aluminum material is formed by positively squeezing the gear and adopting the shaft splitting, hole splitting and constrained splitting method for final pressure forming. The combined test die is used to test various forming process schemes, which improves the filling and reduces the working pressure.
2.3 Experimental chess structure design In order to realize various forming process plans, a combined test die was designed, and its structure is as shown. In order to effectively and economically improve the bearing capacity of the die, a two-layer combined prestressing die is used. The materials of the tooth cavity and the upper and lower bosses are W6Mo5Cr4V2, and the heat treatment hardness is 60-HRC. The upper punch uses internal teeth. The guide sleeve is guided by the guide sleeve, and the guide sleeve is positioned with the positioning pin and the concave mold with high positioning accuracy. The illustrated structure can realize the shaft shunting process, and the punch in the upper and lower punches can be replaced to realize the hole splitting and the constrained splitting and pressing process. The extrusion test was carried out on a 600 kN material testing machine.
A positioning pin; 2 - upper core pad; 3 - convex è ¼ å¿; 4 an upper pressure pad 9 lower core SQ plastic; 11 an external stress luxury test die structure can be seen from the figure, the pressure is not squeezed Large, the fiM is pressed at the final pressure stage and the pressure is sharply increased. Finally, the gear is well formed under the pressure of 600 kN, and the pieces and the piece 2 are shaped into the left and the middle.
Forming the solid billet at the stage of positive extrusion and constrained split final pressure. In the case of forming a solid object, the metal is filled into the cavity due to the restriction of the final pressure, and the forming is ideal. According to the information on the extrusion forming, the larger the diameter of the extruded blank, the larger the gear modulus and the wider the tooth shape, the more favorable the filling of the side cavity.
The solid billet is squeezed and the shunt is formed by the final pressure forming. See the left, and the billet blank is squeezed. The split shunt is formed by the final pressure forming. The two forming effects are also good.
Ms three kinds of shaped gears d. Correct selection of forming equipment tonnage, reasonable mold structure design, considering the elastic deformation of the mold. Increasing the precision of mold manufacturing and the roughness of the surface of the mold are the main factors affecting the forming quality of the gear parts. It is allowed to manufacture the tip and die with high tip to determine the tip of the extruded product and ensure the precision forming of the gear parts. a conventional closed diameter meat extrusion. The extrusion load is large and the gear is formed.
The use of split extrusion can reduce the working pressure and improve the filling of the tooth cavity.
The billet is being squeezed while it is being squeezed. Constrained splitting with a suitable punch forces the gold to flow radially, resulting in good tooth fill and higher gear accuracy.
The design of practical extrusion molding molds is expected to achieve the goal of practical application.
(Below the +4n, the center position of the two is deviated, and i, 2, so the pedal arm is shifted to the left relative to the center position of the brake light switch, which is consistent with the actual situation.
3 Improvement results Based on the above analysis, after obtaining the consent of FAW-Volkswagen, it will be. The size was changed to 20.4 and the corrections and adjustments were made in all aspects of the process and inspection. 20 pieces of test equipment meet the requirements, 400 pieces are produced in small batches, and the position of the pedal arm and the brake light switch no longer appears to be offset, thereby fundamentally solving the offset problem.
Responsible Editor/Chen St (Continued from page 14) Fiat launches new family car in South Africa At the World Auto Expo in South Africa, Fiat Auto Manufacturing of Italy launched a new car called PROECT178, which attracted a lot of interest from visitors.
The PROECT178 sedan, also known as the Fiat World Sedan, is an improved version of Fiat's Uno sedan, designed for front-wheel drive. The designer fully considers the aerodynamic principle and adopts a streamlined model similar to that of a racing car, which speeds up quickly and travels quickly. The car looks small, but the space inside the car is very large. The passengers feel very comfortable sitting inside. It is a boutique car that combines the safety and comfort of a family car with the fast speed of the car.
Fiat is not to be outdone as automakers in the United States, Japan and Germany are rushing to the South African market. This time it launched the “world-class sedan†for the dense highway and good road conditions in South Africa. It is intended to first occupy the South African automobile market and then enter the automobile manufacturing of the 14 member states of the Southern African Development Community and the entire African continent. market.
The general manager of Fiat South Africa said that if the "world car" can succeed in South Africa, Fiat will consider buying and improving the existing car production line in South Africa. The "world car" can be produced in South Africa, so that it can be eliminated. Expensive car import tariffs are more attractive to users in terms of price.
―44―Automotive crafts and materials
Experimental Research on Precision Forming of Gear Cold Extrusion