In the spur gear transmission, the end face coincidence degree X<1, can not guarantee the continuous small number of involute cylindrical gear reducer is a new development in gear transmission technology, because reducing the number of teeth of the pinion can significantly increase the gear ratio of the gear And can reduce the size and weight of the reducer, and has certain technical and economic benefits. When the number of involute cylindrical gears is between 2 and 4, it is called the number of teeth; because of the number of teeth, the small gear and the large gear The gear pair is called a small number of involute cylindrical gear mechanism. For this kind of mechanism, since the number of teeth of the pinion gear is small, firstly, in order to avoid undercutting, a positive displacement of a large displacement coefficient is required; this causes the tip of the tooth tip to be sharpened and the height of the tooth tip is shortened. Secondly, the degree of overlap of the end face is greatly reduced. It is necessary to use a helical gear with a large helix angle and a large tooth width.
Again, due to the relative sliding speed of the tooth surface, it also brings new problems. This paper is to study the theoretical and technical problems of these problems and try to solve them.
The involute profile of the Z1=234 gear cut out using a standard rack-type tool is shown. The dotted line in c is the involute profile of the displacement coefficient X1=0, and the root root is severely undercut, which will seriously affect the transmission quality and the root bending strength. The solid line in the figure shows the tooth profile cut out with a larger displacement coefficient of 1.05).
The number of teeth of the involute spur gear mechanism is small. Since the number of teeth of the small gear is small, the end face meshing condition of a pair of small-numbered involute helical gear mechanism is shown at 1 at the two tooth profile point B1, the pinion gear The sliding coefficient of the top is the maximum value 1max, and the sliding coefficient of the root of the large gear also reaches the maximum value. Due to the large relative sliding, the wear and heat of the lead are severe, and the temperature of the meshing zone is high. To this end, it should be designed to have a backlash engagement for storage of lubricating oil and liquid lubrication that facilitates the formation of a dynamic oil film. It is known that the gear tooth thickness after the displacement is large and the full tooth height is less than the standard tooth height. From the relative ratio between the tooth thickness and the tooth, the large gear should not adopt the negative displacement. In this case, the node P is located in the meshing zone. In addition, the node is externally engaged as shown. Because the two gear end faces are displaced by T, the center-to-center variation coefficient yt>the bending strength of the positive transmission and the top circular tooth thickness Sa of the contact strength displacement gear decrease with the increase of the positive displacement coefficient X, and both are relatively improved. But the gears must be designed, manufactured and used in pairs. The top round tooth thickness is when the pinion number Z1=2~4, Table 1 selects X, 1=At this time, the tooth tip becomes sharp, and the tooth top height ha1 is shortened.
After selecting X, 1, X, 2 is to ensure the node external meshing principle to determine X, 2 see, in order to ensure the node external meshing, the starting meshing point B2 should be located to the left of node P. That is, when the B2 point coincides with the node P, Ta2=T, so the meshing conditional position of the node (including the node) can be obtained by the geometric parameter conversion of the involute cylindrical helical gear, and the round pressure angle can be obtained.
0 (that is, the top of the tooth tip), by 1990 2 Sun Hao et al. Mechanical Principles M. Beijing: Higher Education Press, 1992 丨 3 West Germany Sherman SMS (SMS). Compilation of design data for cylindrical gears and worm gear reducers. M. Xi'an Heavy Machinery Research Institute, 1988 (continued from page 952) 3 Liang Baichuan. Multi-sensor information fusion decision making research. Aerospace Electronic Confrontation, 1994 (3) 4 Wang Jiangping. Research on fault diagnosis method of diesel engine oil supply system based on information fusion technology D. Xi'an Jiaotong University,1997.5 8 Shen Qing et al. Introduction to Pattern Recognition M. Changsha: National University of Defense Technology Press, 1991 1:2000-
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