The forging experiment is carried out by hot forging. Firstly, the forging die is processed, and then the forging experiment is carried out on the large and small wheels of spiral bevel gear by using the forging press of a company. In view of the large modulus of spiral bevel gear, cold forging requires a super large press with a loading force of 10000 tons, so the hot forging cold finishing method is adopted, Firstly, the blank is forged into a shape close to the forging, and then the cold precision forging die is used for finishing to obtain the final forging; The simulation results are compared with the experimental results, which has certain guiding significance for forging production.
1. Introduction to experimental equipment
The forging press of a gear factory is used in the forging experiment. As shown in Figure 1, the 1000 ton friction press is used. Its working principle is the screw press driven by friction (double disc friction press is used in this experiment), which uses the contact transmission of flywheel and friction disc, and works with the help of the relative movement of screw rod and nut. The equipment has a wide range of application, structure, installation The operation is relatively simple. It is a kind of equipment widely used in forging workshop.
2. Forging test process
The experiment was carried out by die forging and hot forging process, and then the tooth profile was trimmed again by cold finishing die.
Firstly, the forging die is made, the NC machining method is adopted, the tool path and feed rate are designed by software, and the die of spiral bevel gear is milled on the machining center. For the tooth shape part of the die, the secondary cutting method is used, and the allowance is reserved for 2mm on one side to obtain the hot forging die. Then, the cold finishing die is processed in the same way, without allowance, and the three-time cutting method is adopted, The last cutter adopts a small-diameter ball end milling cutter, and each feed is reduced to process a cold finishing die.
Then use the heat treatment method to process the mold again to improve the strength of the mold, but during the heat treatment, try to improve the requirements and reduce the deformation of the mold. The obtained large wheel upper mold is shown in Figure 2. The shape of the cold finishing upper mold is the same, but the size follows the mold model.
Install the fabricated die and blank according to the forging process and carry out forging test. Firstly, pre forge according to the hot forging method, and then replace the die for finishing forming. The produced forgings are shown in Figure 3 and the partial magnification of forgings is shown in Figure 4.
It can be seen from Figure 3 that the tooth shape of the forged big wheel is good without obvious defects. After local magnification, it can be seen from Figure 4 that there are blackened places in some positions. After analysis, it may be caused by the high temperature during hot forging or the uneven material of the blank, without folding, pores and other defects, indicating that the blank filling rate is high and meets the forging expectation.
Combined with the simulation and experimental results, it can be seen that the large wheel in this example can be processed by hot forging cold finishing. The precision of the forged spiral bevel gear is high. Similar to the simulation results, there are no obvious defects such as folding and pores in the gear teeth, and the forging is relatively successful.