CN100365322C - micro-segment gear - Google Patents

Abstract

The invention relates to a gear, specifically a micro-segment gear, which is characterized in that the tooth profile curve is smoothly connected by micro-segment curves or micro-segment straight lines, and the minimum number of teeth is 3 teeth. Compared with the involute gears commonly used at present, micro-segment gears are not only suitable for general transmission occasions, but especially suitable for motion and power transmission in high-speed, heavy-duty or miniaturized occasions.

Description

micro-segment gear

technical field

The invention relates to a micro-segment gear applied in the field of mechanical transmission and power transmission.

Background technique

Gears are indispensable and important parts of all kinds of industrial machinery, automobiles, ships, locomotives, airplanes and other machinery and devices. It is one of the main forms of transmitting motion and power in mechanical equipment, and its performance largely determines The quality and level of mechanical products.

At present, involute gears are the most used. Involute gears have many advantages, such as simple manufacture, good interchangeability, easy to change positions, etc., but their disadvantages are also obvious, such as low strength, especially low contact strength. , The minimum number of teeth is large, so that the volume is larger, etc. The minimum number of teeth without undercutting is 17. After taking measures such as displacement, the minimum number of teeth is difficult to be less than 12, so it cannot meet the requirements of high speed, heavy load and miniaturization. At present, other toothed gears that have been applied in production practice also have this problem, such as: arc gears, cycloid gears, etc. Although arc gears have basically solved the problem of low contact strength of involute gears, they have insufficient bending strength and must be made into helical gears.

Contents of the invention

The purpose of the present invention is to provide a micro-segment gear with a minimum number of teeth of 3 teeth, high gear contact strength and easy processing.

The technical solution that realizes the above-mentioned purpose of the invention is as follows:

Micro-segment gear, the tooth profile curve is smoothly connected by micro-segment curves or micro-segment straight lines, the length of the micro-segment curve is less than 1 micron, and the tooth profile at the tooth root of the gear is a concave tooth profile curve, which is characterized in that : The minimum number of teeth is 3 teeth;

When the number of teeth is 3-8 teeth, the range of the addendum height coefficient is 1.1-1.4, the dedendum height coefficient is 0.6-0.9, the tooth thickness increases to 0.55πm-0.7πm, and the slot width is 0.3πm-0.45πm, where m is the modulus.

The micro-segment curve is an involute curve and can be replaced by a micro-segment straight line.

The gear is a spur gear or a helical gear.

The structure of the tooth profile curve of the micro-segment gear reference rack of the present invention: as shown in Figure 1, it is a schematic diagram of the composition of the micro-segment gear reference rack with a small number of teeth. In Fig. 1, the micro-segment m ₁ S ₁ is centered on o ₁ , o ₁ o ₁ ′/2 is the involute on the base circle of the radius, the micro-line segment S ₂ m ₁ is the involute on the base circle with o ₁ ′ as the center and o ₁ o ₁ ′/2 as the radius , the micro-segment S ₂ m ₂ is the involute on the base circle with o ₂ as the center and o ₂ o ₂ ′/2 as the radius, and so on, the basic tooth shape of the micro-segment rack is formed.

The properties of the curve are determined by three independent parameters: r _b0 , α ₀ , δ, which are called the initial base circle radius, the initial pressure angle and the parameter pressure angle respectively. There is no certain limit to their values and can be selected according to the needs.

The formation of micro-segment gear tooth profile curve: According to the basic gear meshing principle, the corresponding gear tooth profile curve equation can be deduced through the reference rack and gear meshing from Figure 2:

In the formula: d＝x ₁ +y ₁ /tgα _i

x ₁ , y ₁ : coordinates of the standard micro-segment rack tooth corridor curve point;

 ₂ : The rotation angle of the micro-segment gear from the initial position;

d: When the corresponding micro-segment gear rotates  ₂ angles, the moving distance of the standard micro-segment rack;

r ₁ : Radius of the pitch circle of the micro-segment gear;

x ₂ , y ₂ : the coordinates of the point on the tooth corridor curve of the micro-segment gear meshing with the point (x ₁ , y ₁ ) on the standard micro-segment rack;

α _i : Pressure angle at the meshing point.

The micro-segment gear constructed in this way has a convex-concave meshing form as a whole, that is, the tooth top of each gear is divided into a convex tooth gallery, and the dedendum part is a concave tooth gallery. According to the selected initial parameters, each dental corridor is generally composed of thousands or even tens of thousands of micro-segment curves, and the length of each micro-segment is 1 micron or even shorter.

For micro-segment gears with a small number of teeth greater than 8, the structure does not need to be adjusted, while for micro-segment gears with a small number of teeth between 3 and 8, structural adjustments are required. The specific measures are as follows:

A. Decrease the dedendum height coefficient and increase the addendum height coefficient, but the sum of the two remains unchanged. Similarly, in order to ensure correct meshing, the corresponding large gear meshing with it should also be changed accordingly, that is, increase the dedendum height coefficient and reduce the addendum height coefficient.

B. Increasing the tooth thickness of the pinion means reducing the tooth thickness of the pinion rack tool, while the sum of the tooth thickness and the tooth space width remains unchanged. The large gear meshing with it should also be changed accordingly, that is, reduce the tooth thickness of the large gear and increase its tooth space width.

Beneficial technical effect of the present invention is embodied in following several aspects:

Compared with the involute gears commonly used at present, micro-segment gears are not only suitable for general transmission occasions, but especially suitable for motion and power transmission in high-speed, heavy-duty or miniaturized occasions.

1. Compared with involute gears, micro-segment gears not only have high contact strength, but also have high bending strength. Since the bending strength of the gear is mainly related to the thickness of the dedendum, and the contact strength is mainly related to the comprehensive radius of curvature, the tooth profile of the micro-segment gear we constructed not only has a thicker dedendum thickness, but also adopts a convex-to-concave meshing form , the comprehensive curvature is zero at the construction point, so this gear has high contact strength and bending strength. The relevant experiments we conducted also confirmed this point.

Figure 3 shows the comparative experimental data of the bending strength of the two gears, from which it can be seen that the bending bearing capacity of the micro-segment gear is significantly higher than that of the involute gear.

The contact fatigue strength experiment we have done also shows that under the same working conditions, the contact strength of micro-segment gears is obviously higher than that of involute gears.

2. High transmission efficiency. Experimental research on transmission efficiency shows that under the same working conditions, the transmission efficiency of micro-segment gears is about 3% higher than that of involute gears, which is very important for mechanical transmission, especially high-power transmission under high-speed and heavy-load conditions. significance. Figure 4 is a comparative experimental curve of two gear transmission efficiencies at 1000 rpm (the dotted line in the figure is a fitting curve made according to the experimental data).

3. The minimum number of teeth is small, which is suitable for miniaturization. Studies have shown that the minimum number of teeth of micro-segment gears is 3, so that under the same modulus, the size of micro-segment gears can be much smaller than that of involute gears. At present, we have processed micro-segment gears with a minimum number of teeth of 3. Therefore, micro-segment gears are especially suitable for occasions requiring miniaturization.

Description of drawings

Figure 1 is a schematic diagram of the formation of micro-segment rack tooth profile;

Fig. 2 is a diagram of the meshing coordinate system of the micro-segment rack and pinion;

Fig. 3 is a comparison experiment result diagram of the bending strength of the involute gear and the micro-segment gear;

Fig. 4 is a comparative experimental data diagram of two gear transmission efficiencies at 1000 rpm.

Figure 5 is a transmission diagram of 3-tooth gear meshing.

Detailed ways

The present invention will be described in further detail through the embodiments below in conjunction with the accompanying drawings.

Example 1:

Micro-segment gear transmission with a gear ratio of 11:51. The pinion gear is a gear with a small number of teeth that has not been adjusted in structure (that is, other parameters such as addendum height coefficient, slot width, etc. do not require special treatment except for the tooth shape factor), and the large gear meshing with it has 51 teeth, which is also a micro-segment gear . It can be a straight toothed gear or a helical toothed gear.

Example 2:

A pair of micro-segment gears for meshing transmission, the number of teeth of the small gear is 3, the number of teeth of the large gear is 12, and the module is 6. The addendum height coefficient of the small gear is 1.4, the dedendum height coefficient is 0.6, the indexing round tooth thickness is 0.7πm, and the tooth groove width is 0.3πm; the addendum height coefficient of the large gear is 0.6, and the dedendum height coefficient is 1.4. The indexing circular tooth thickness is 0.3πm, and the slot width is 0.7πm. (See Figure 5)

Example 3:

A pair of micro-segment gears for meshing transmission, the number of teeth of the small gear is 8, the number of teeth of the large gear is 20, and the module is 2. The addendum height coefficient of the pinion is 1.1, the dedendum height coefficient is 0.9, the indexing circular tooth thickness is 0.55πm, and the tooth slot width is 0.45πm; the addendum height coefficient of the large gear is 0.9, and the dedendum height coefficient is 1.1. The indexing circular tooth thickness is 0.45πm, and the slot width is 0.55πm.

Claims (1)

1. Micro-segment gears, the tooth profile curve is formed by smooth connection of micro-segment curves or micro-segment straight lines, the length of the micro-segment curve is less than 1 micron, and the tooth profile at the tooth root of the gear is a concave tooth profile curve, which The feature is that the minimum number of teeth is 3 teeth; When the number of teeth is 3-8 teeth, the range of the addendum height coefficient is 1.1-1.4, the dedendum height coefficient is 0.6-0.9, the tooth thickness increases to 0.55πm-0.7πm, and the slot width is 0.3πm-0.45πm, where m is the modulus.

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