Surveying and mapping method of spur gear

In order to make the gear rotate in both directions, the tooth profiles on both sides of the tooth are composed of involute curved surfaces with the same shape and opposite direction. The names and symbols of each part are: tooth top circle, tooth root circle, tooth groove, tooth thickness, tooth pitch, module m, indexing circle D, tooth top and tooth root, and top clearance. Spur gear is one of the most common gears in actual production and use, and damage is inevitable in the process of use. Therefore, it is necessary to make a new gear that is the same as the original one. Due to various reasons, the customer cannot provide the drawings of the required spur gear. In order to ensure the normal use of the processed products, it is necessary to accurately map the gear. Mapping is a complex work, Because there are few materials to introduce the surveying and mapping of spur gears, it is inconvenient to consult. Through the actual operation, the working experience and methods of Surveying and mapping of spur gears in several actual production are summarized. The introduction is as follows:

First of all, although there are many parameters and dimensions of spur gears, the standard systems of various gears stipulate that modulus or diameter pitch is used as the calculation basis of other parameters and dimensions of each part. Therefore, the surveying and mapping work should try its best to accurately determine the size of modulus or diameter joint. At the same time, the pressure angle is the basic parameter to determine the tooth profile, and accurate determination is equally important.

Secondly, we need to know the usage and production country of the surveyed gear, so that we can estimate the standard system adopted by the gear. Generally, China, Japan, Germany, France, the Czech Republic and the former Soviet Union adopt the modular system, and the tooth profile of the gear can also be observed. If the tooth profile is curved and the bottom of the tooth groove is narrow in a circular arc, it can be preliminarily determined as the modular system, and the standard pressure angle is mostly 20 degrees; The United States and Britain adopt diameter control, with standard pressure angles of 14.5 degrees and 20 degrees. After observing that the tooth profile is flat and the tooth groove bottom is wide and the arc is small, it can be preliminarily determined as diameter control, with pressure angle of 14.5 degrees. It can also be compared with gear hob or standard rack sample to determine which pressure angle is. After knowing the above situation, we can carry out actual mapping.

The above are the surveying and mapping methods of spur gears commonly used in practical work. It is best to check each other with two methods when using them, so that the determined modulus or diameter pitch is more accurate. At this time, the surveying and mapping work is basically completed. Special attention: the above surveying and mapping methods are carried out when we can determine or investigate the standard system adopted by the gear in advance. If the “everything is unknown” of the gear, the above methods can only be used for reference, and then comprehensively determined through other ways. It is believed that the above surveying and mapping methods are of some help to the colleagues who just participated in the work or conducted the surveying and mapping of spur gears for the first time, which is worthy of reference.

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