Analysis on key manufacturing technology of large herringbone gear

1. Technical analysis of forging process

In offshore engineering, the requirements for large herringbone gears are relatively high. The original conventional large spur gears can not meet the needs of offshore engineering because of their large weight, gear width and thickness. Therefore, free forging technology is mainly used. In this process, 10000 tons of water and oil are mainly used to manufacture the press. For example, the first 10000 tons of water press in China is also manufactured after a series of processes such as blank opening, pier thickening, punching and reaming on the mandrel. When the free forging technology is used to manufacture large herringbone gears, there is a large forging allowance, and a large number of materials are required, and the corresponding production cost can not be controlled, which leaves a lot of problems for the subsequent processing. Large herringbone gear is a ring-shaped part because of its small width and thin tooth wall. Therefore, the ring rolling forging technology can be used in the manufacturing process. This technology is a new processing technology for the forming of ring parts.

The rolling wheel rotates actively to drive the ring gear blank to rotate, and then the ring blank drives the core to rotate. At the same time, the distance between the rolling wheel and the middle position of the core will be smaller and smaller, which indicates that the thickness of the annular blank is gradually decreasing and the diameter is gradually expanding until the required herringbone gear section shape is formed, and this process is completed. Forging technology and free forging technology have relatively little margin. At this stage, the application range of ring grinding equipment is very wide. For example, the diameter of ring grinding machine produced by German SMS company can reach more than 9m. Because the weight of ring grinding blank manufacturing technology has about 25% allowance compared with free forging, the application of ring grinding technology in large herringbone gear can save manufacturing cost to a great extent.

2. Heat treatment technology of large herringbone gear

In the production process of large herringbone gears, quenching and tempering treatment is mainly aimed at obtaining a more detailed and homogeneous tempered cable structure and achieving the performance required by integrated machinery. In the quenching and tempering process of large thin-walled herringbone gear, the main difficulty to control is the uniformity of workpiece deformation and hardness. Generally, the hardness of large thin-walled herringbone gear needs to be controlled between 240-280hb. In the process of treatment, the temperature of heat treatment and quenching needs to be controlled between 860 ± 5 ℃ and guaranteed for about 6 hours. After the water-soluble quenching liquid is cooled, the tempering needs to last between 630 ± 5 ℃ for 12 hours, and then air cooling. In the process of heat treatment technology, the heat treatment equipment needs a large well chamber furnace, the maximum temperature should be controlled at 1050 ℃, the furnace loading should be controlled at about 45t, and the furnace temperature should not exceed 5 ℃.

In addition, the hardness of herringbone gear should be controlled between 240-280hb, and the mechanical properties should be kept good. The most critical control point in heat treatment technology is to control the flatness of herringbone gear installation platform first; After the thin-walled herringbone gear is processed, it is necessary to check the padding of the herringbone gear plane and the installation platform, and reasonably control the furnace loading according to the actual situation of the workpiece, so as to not only ensure the processing quality, but also ensure that the production and manufacturing cost is controlled at the lowest level. In the process of heat treatment, the temperature of each part in the furnace needs to be controlled to ensure that the overall temperature difference in the furnace is less than 5 degrees, and to ensure the normal operation of the mixing equipment in the furnace.

3. Tooth profile processing technology of large herringbone gear

In the process of large herringbone gear hobbing, in order to improve its processing efficiency, a number of herringbone gears with the same parameters need to be placed together through tooling in the production process and processed through one hob, which can not only control the hob outlet time, but also improve the processing and production efficiency. In addition, It can also solve the problem of measuring the common normal of helical gears.

In the process of gear hobbing technology cutting, mass production can improve the efficiency of production and manufacturing. At this time, the disk milling props can be installed on the gear hobbing machine through disk milling, and the disk milling cutter needs to be set to a large cutting amount. At the same time, the linear speed also needs to be set to the highest. In this way, the blade can be replaced, and the cutting efficiency will be greatly improved, The roughness of the tooth surface will also be significantly improved. However, the universality of this disc milling cutter is relatively poor, and it is more suitable for mass production in the processing factory of large herringbone gear. In the process of application, it can be classified and processed according to the theoretical data of modular disc milling cutter, and the application range of the cutter can be adjusted.

4. Technical analysis of large herringbone gear combination

Before assembling large herringbone gears, it is necessary to select appropriate common normal value according to the drawings of herringbone gears, and select left-right herringbone gears whose deviation of common normal value meets the standard; Before the herringbone gear assembly, the burrs and sundries on the left and right herringbone gears need to be removed. During the combination of herringbone gears, the left and right herringbone gears need to be aligned. The position of the left and right herringbone gears can be controlled by means of two center alignment inspection. After the herringbone gear combination is completed, the combined herringbone gear needs to be clamped by means of mechanical or combined bolt connection of the left and right herringbone gears. After the above combination process is completed, the large herringbone gear needs to be matched, precision drilled and reamed, so as to ensure the combination quality of the large herringbone gear.

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