The main parameters of Gear (including cylindrical Gear and bevel Gear), such as the number of teeth, modulus, tooth width, tooth height, helix angle, index circle diameter, etc., are determined by the strength calculation, and the structural design mainly determines the spokes, Form and size. Gear structure design, to consider the processing, assembly, strength, reuse and many other design criteria, through the spoke, the hub shape, size transformation, designed to meet the requirements of the gear structure. The size of the gear is the main factor affecting the size of the spoke and hub. It is usually the first to determine the appropriate structure according to the gear diameter, and then consider other factors to improve the structure, the details of the details of the details of the structure, see the relevant manual.
The gear structure can be divided into four basic forms:
1, gear shaft
For small diameter Gear, if the distance from the bottom of the keyway to the tooth root is xx ≤ 2.5
, Bevel gear x ≤ 1.6m, m It is noteworthy that the gear shaft, although the assembly is simplified, but the overall length, to the tooth processing inconvenience, and the gear is damaged, the shaft also with the scrapped, is not conducive to reuse The Therefore, when x (cylindrical gear) or xm (bevel gear), the gear should be manufactured separately from the shaft. > 1.6> 2.5 for the modulus), then the strength here may be insufficient, prone to fracture, this time should be made of gear and shaft, called the gear shaft
2, solid gear
When the width of the spoke and the tooth width is equal to get a solid gear structure (Figure 2), its structure is simple, easy to manufacture. The same time as the above-
(A) the diameter of the crested circle da ≤ 200mm; (b) the special requirements for reliability; (c) reduce the noise at high speed.
In order to facilitate the assembly and reduce the edge of the stress concentration, hole edge and tooth tip edge should be cut chamfer. For bevel Gear, the width of the hub should be greater than the tooth width, in order to facilitate the processing of clamping.
, Web Gear
When the tooth top diameter damm, can be made of web-type structure to save material, reduce weight. Taking into account the need for clamping and handling during processing, the web is often symmetrical out of 4 to 6 holes. When the diameter is small, the webs are often used for forging, and the batch is used for free forging (Fig. 3). When the batch is large, the die is used for large diameter (Figure 3. When the diameter is large or the structure is complicated, Cast steel and other materials from casting.
Gear is the most widely used in modern machinery, a mechanical transmission parts, metal cutting machine tools, engineering machinery, metallurgical machinery and automotive, instrumentation, household appliances, etc. have Gear. The Gear are engaged with each other by means of Gear to transfer the movement and power between any two axes of space and to change the form and speed of movement. Gear drive use a wide range of transmission ratio is constant, high efficiency, long service life.
In the design and manufacture of mechanical parts products, not only consider the performance of materials to meet the working conditions of parts, so that parts durable, and requires a better material processing technology and economy in order to improve the production efficiency of parts, Cost, reduce consumption. If the gear material selection and improper heat treatment, there will be parts of the premature injury, or even failure. Therefore, how to choose a reasonable, the use of metal materials and appropriate heat treatment is a very important work.