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Application of Coal Mine Machinery Planetary Gear Reducer in Pipe Jacking Machine Jiang Fenye (Shanghai Branch of Coal Science Institute, Shanghai 200030).
Middle drawing number: TD421. 1Overview With the continuous development of municipal construction in China, the underground pipeline laying projects such as sewage, water, gas, electricity and cables in the city have become a regular work.
In recent years, on the basis of introducing and digesting foreign advanced technology, China has developed a variety of non-excavation technology underground pipe laying equipment and a pipe jacking machine based on the national conditions. It is an advanced non-excavation technology equipment integrating mechanical, hydraulic, electronic control (including PLC), laser and measurement. It is not only efficient, but also does not affect the ground environment and traffic. Since the jacking machine is constructed continuously for a long distance in the underground, its reliability and safety requirements are very high.
2 Cutting transmission device The structure of the pipe jacking machine is limited by the diameter of the pipe to be laid, so it is difficult to design the cutting gear to the heart of the pipe jacking machine. In particular, the small-diameter pipe jacking machine with a diameter of 900 mm or less has a small effective space and high strength requirements. It is more difficult to arrange the cutting transmission device that satisfies the strength within a limited space.
Depending on the size of the pipe jacking machine, each set of cutting gears consists of a set of coaxial output drives or a combination of multiple sets of power output drives. Each group of devices consists of a motor, planetary gear reducer, cylinder, drive shaft set, tool holder, cutter head and other major components. As shown.
According to the earth pressure situation, the axial expansion and contraction movement prevents the ground from settling or bulging and maintains the pressure balance.
3 The structural characteristics of the planetary reducer Due to the working conditions, the speed ratio of the reduction gearbox is larger and the size is smaller.
Therefore, the gearbox adopts the planetary transmission structure, which is very reasonable. Compared with the traditional fixed-shaft transmission structure, it not only has small size, but also has large bearing capacity, stable mechanical performance and excellent transmission effect. This is a relatively mature deceleration. Structure.
The planetary gear reducer designed and developed by the Hengtong Transmission Engineering Branch of Shanghai Coal Science and Technology Co., Ltd. is designed for the municipal engineering top pipe jacking machine. After actual use, it is strictly evaluated, with reliable performance and long service life.
Serial number power / kW transmission ratio output torque / Nm output speed Zrmin-1 top tube tunneling machine cutting gear transmission planetary gear reducer is composed of three-stage 2KH planetary gear transmission, transmission ratio between 150 ~ 500, The output speed is 3~10rinin and the output torque is up to 36kNm. The advantage of planetary transmission is the equal amount of shunting of the transmitted power.
In order to achieve a reasonable load sharing, the reducer is designed as a double floating structure of the sun gear and the carrier. The floating amount is realized by a reasonable involute spline flank fit clearance, which can maximize the power equal split between the planetary wheels. , obtain the minimum load distribution coefficient, and eliminate the influence of inevitable errors due to manufacturing, heat treatment deformation, assembly, and the like.
Due to the limited space, the reducer is small in size, but the strength cannot be reduced; and because the transmission ratio is required to be large, the number of teeth of the sun gear is small, generally about 12 teeth, and sometimes even less. To this end, we design the gears as hard tooth surfaces. The external gear is cut with a low carbon alloy disc holder. And through the cylinder E tool holder can fciSh structural steel, through carburizing and quenching h to achieve the hardness of the tooth surface hard pf toughness can reach more than 6 grades, can improve the transmission efficiency. After grinding the teeth, the gear teeth are further subjected to enhanced shot peening to add compressive stress to the tooth surface and the tooth root, which improves the durability limit of the gear teeth and prolongs the service life. The internal gear has a large number of stress cycles, and the gear teeth should have sufficient wear resistance. Therefore, the medium carbon alloy structural steel is used, and the nitriding treatment is performed after quenching and tempering, so that the hardness requirement is met, the wear resistance is good, and the precision is also up to 7 Above level. In addition, all external gears are designed to have a large circular arc (R>0.4). Specially designed retaining hobs are used for machining, as shown. The large rounded corners can reduce the stress concentration, and the roots are not ground. The gear grinding arcs are connected with the large rounded corners of the tooth roots to prevent burns and cracks, and the bending fatigue limit is greatly improved.
In order to reduce the axial and radial dimensions of the reducer, the first and second stage planet carriers are designed as a single disc structure, that is, the planetary wheel mandrel is integrated with the planet carrier, and the output torque of the first stage carrier is The inner gear is meshed with the second stage sun gear. As shown. The planet carrier material is made of cast steel medium carbon alloy structural steel with quenching and tempering hardness of HB280 ~ 320. The position of the planet carrier mandrel and the parallelism between the axis and the central axis are guaranteed by coordinate boring machine processing, and static balance test is required before assembly. The floating amount is used to satisfy the unevenness coefficient of the tooth surface design (design value is 1.1 to 1.15). This design satisfies the space requirement.
4 Application effect Since 1995, the developed top pipe jacking machine has been used for 20,000 000, 200 000, and the gear reducer for cutting transmission has adopted planetary gear structure. The practice has proved to be successful, especially in harsh conditions. The reliability of the lower equipment, which is inseparable from the compact structure of the planetary reducer, small size, large transmission ratio and high efficiency.