Research status of driving spiral bevel gear blank of automobile rear axle

Automobile rear axle gear is an important part of automobile drive system. Due to its poor working condition and heavy load, it is a vulnerable and consumable part of automobile parts. During the whole service period of a vehicle, many gears are often lost.

Once the gear is damaged, it is very difficult to replace it. The quality of the gear blank forging directly determines the stability of the transmission and the service life of the gear. In the early stage, the methods of producing driving gear blank of automobile rear axle in China include forging with friction press, forging with die hammer and forming with hot die forging press, all of which have the disadvantages of large equipment investment and low material utilization. As the driving helical gear of automobile rear axle belongs to rod forgings, the cross wedge rolling technology suitable for the production of rod forgings has become popular. At present, most rod forgings are produced by cross wedge rolling. Four main forming methods of driving spiral bevel gear blank of automobile rear axle are described: hot die forging (cross forging), warm forging (drawing blank → top pier forming), cross wedge rolling, cross wedge rolling → top pier forming. The forming processes of four forming methods are introduced respectively. Finally, each forming process is compared and analyzed. The hot forging and warm section are also discussed, and it is pointed out that,

The decarburization speed of iron and steel shall be accelerated when the oxidation temperature is ≥ ℃, and the decarburization speed shall be as low as possible when the oxidation temperature is ≤℃, and the decarburization temperature shall be as low as possible when the oxidation temperature is ≤℃. At present, the most advanced shaft forging technology at home and abroad is cross wedge rolling → closed die vertical forging. This process not only has high material utilization rate, but also has higher production efficiency than drawing blank by forging. This paper mainly improves the existing process of forming the driving spiral bevel gear of automobile rear axle on the hot die forging press, and points out that the forging of automobile rear axle driving spiral bevel gear produced by existing methods has large diameter and section difference, the continuous part of cone head and cone rod often has folding defects, the top of cone tail small head is not fully filled, the flash distribution is uneven, and the material waste is serious. The existing process includes heating, roll extrusion, upsetting, final forging and edge cutting.

The existing process is improved as follows: heating → vertical pre forging → horizontal final forging → trimming. Compared with the existing process, the new process has one less roll extrusion process. The original rotary ° horizontal pre forging after roll extrusion is changed to direct vertical pre forging after blank heating, and a list is given to compare the economic and technical indexes such as material utilization of the new and old processes. The qualified rate of forgings has been increased from about to, the appearance quality of forgings has also been significantly improved, and the cost of forgings has been greatly reduced. Taking the forming of the driving spiral bevel gear blank of the new automobile reducer as an example, using software analysis, adopting the forward and reverse extrusion die structure and relevant process parameters, the forward and reverse extrusion is realized on a hydraulic press, and the blanking weight is reduced from each piece of the existing process to each piece. The technological process is given in the literature: sawing, blanking, hot extrusion and one-time forming. The forming process is simulated by software, the simulation process is given, and the factors affecting the simulated forming, temperature and friction coefficient are analyzed. It is pointed out that temperature is an important factor in hot working. It not only directly affects the mechanical properties, microstructure and flow of materials, but also relates to the problem of energy consumption; Friction is an inevitable factor in the forming process. The optimal friction coefficient is given as. The patent uses two processes: roll forging blank making and final forging forming. The roll forging blank adopts four roll forging steps. The final forging forming process is to put the roll forging in the fourth station into the final forging forming die. Under the action of punch pressure, the blank is formed by aggregating downward along the inner wall of the sleeve die, and then ejected through the ejector rod after demoulding.

This method has the advantages of low noise, high production efficiency and material utilization in forming production. The disadvantages of hammer drawing equipment, such as high tonnage, high noise, many times of striking, low production efficiency, poor labor environment, rough surface of formed blank and low straightness, are improved. At the same time, it avoids the disadvantages of easy bending, large flash and low material utilization during general die forging. It is a more advanced technology at home and abroad. This paper expounds the production, processing, numerical simulation and production status of similar parts of bevel gear, and points out that how to improve the quality of gear forgings, reduce machining allowance and shorten production time is still the main research direction. The figure shows the driving spiral bevel gear blank of automobile rear axle produced by ZHY Gear.

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