WO2000000758A1

WO2000000758A1 - Worm with modified threads

Info

Publication number: WO2000000758A1
Application number: PCT/CN1998/000104
Authority: WO
Inventors: Yaxiong Zhang; Lin Qi
Original assignee: Tianjin Everbest Gear Co., Ltd.
Priority date: 1998-06-29
Filing date: 1998-06-29
Publication date: 2000-01-06
Also published as: AU8099598A

Abstract

The present invention concerns a worm gear unit in which the crests of the threads of the worm are circumscribed by a cylindrical or drum-shaped surface and the enveloping surface of the pitch diameter of the threads is revolved by a curve. In accordance with the present invention, the worm has modified spiral teeth whose thickness and height both vary. In operation, the load capacity and driving efficiency are considerably increased because there are more spiral teeth gradually getting into, as well as out of, engagement with the worm wheel compared with the standard cylindrical worm. Additionally, there are less spiral teeth getting into engagement with the worm wheel than the standard enveloping worm, which fact brings forth many advantages like less heat generating, lubricant stirring loss reduced, rarely sensitive to the mounting dimensions, easy manufacturing and highly economical.

Description

Variable gear worm technical field

The invention relates to a worm auxiliary member of a gear transmission mechanism. Background technique

The worms currently used are divided according to the shape of the helical surface of the helical teeth on the worm shaft. There are mainly involute worms, extended involute worms, and Archimedes worms. They are all cylindrical surfaces. These worms, as well as the K-shaped cylindrical worms and circular-arc cylindrical worms that have appeared in recent years, can be called cylindrical worms. Due to the small number of teeth that are simultaneously meshed in the transmission, it has the advantages of small heat generation, low installation and adjustment requirements for the center distance and axial position, but its shortcomings are small load carrying capacity and low transmission efficiency. Therefore, toroidal worm and worm gear transmission has appeared, and the toroidal worm is also composed of the shaft body and the spiral teeth thereon. Its tooth top surface and indexing circle are not cylindrical surfaces, but a circular arc revolved around the axis of the worm. Arc turning surface. Compared with ordinary cylindrical worm and worm gear drive, toroidal worm and worm gear drive has the advantages of less wear, high transmission efficiency, more teeth at the same time, large bearing capacity, and can withstand impact loads. However, its disadvantages are: The meshing heat is large, and the corresponding box is large. The oil capacity is high and more heat sinks are needed. Due to the rise in oil temperature, the service life of the bearing is reduced; the installation sensitivity of the worm pair to the center distance and axial position is strict, which leads to an increase in manufacturing costs.

Therefore, in order to overcome the deficiencies in the prior art, an object of the present invention is to provide a This kind of variable tooth worm by-product has both the advantages of the above two types of worms, low heat generation, low installation and adjustment requirements for center distance and axial size, large load capacity, high transmission efficiency, easy manufacturing and good economy.

The following technical solutions can be adopted to achieve the purpose, that is, the present invention proposes a variable tooth worm, which is still composed of the shaft body and the spiral teeth thereon, but its tooth top surface is a cylindrical surface or a drum-shaped surface. The graduated circle is a curved surface of revolution. The tooth thickness and tooth height of the finished worm product vary.

According to the variable tooth worm according to the present invention, no matter whether the tooth top surface is a cylindrical surface or a drum-shaped surface, in the length direction of the worm, the teeth at both ends are the thickest and the shortest, gradually transitioning to the middle, and the center teeth are the thinnest. highest. Therefore, its performance is completely between the cylindrical worm and the toroidal worm. It has the advantages of both and avoids the disadvantages of the two.

On the premise of meeting the above structural requirements, as for the shape of the helical surface of the helical teeth on the variable-worm worm shaft body, the specific structural form of other parts, the modulus of the worm, the number of heads, the direction of rotation and the overall size, etc., can be based on Needed for use, set as appropriate, they have no effect on the performance of the variable gear worm.

As in the prior art, the manufacturing of worm gears can be performed by cutting with a hob equivalent to the shape of a variable worm. Overview of the drawings

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Figure 1 is a schematic structural diagram of a cylindrical worm gear;

FIG. 2 is a schematic structural diagram of a drum-shaped variable tooth worm. Best Mode of the Invention Example 1

As shown in FIG. 1, the variable tooth worm according to the first embodiment of the present invention includes a shaft body 1 and helical teeth 2 provided on the shaft body. Its tooth top surface is a cylindrical surface, and the graduated circular curved surface of the tooth surface is The elliptical surface of revolution obtained by rotating a section of elliptic curve around the axis of the worm. Other structural elements can be set as appropriate according to the prior art.

The tooth top surface of the variable tooth worm may also be a drum surface.

Example 2

The tooth surface graduation circle of the variable tooth worm is a parabolic revolution surface obtained by rotating a parabola around the axis of the worm. Others are the same as in Example 1, and can form a variable tooth worm member whose tooth top surface is a cylindrical surface or a drum surface.

Example 3

The tooth surface indexing circle of the variable tooth worm is a hyperbolic revolution surface obtained by rotating a hyperbola around the axis of the worm. Others are the same as in Example 1, and the variable tooth worm can be composed of a cylindrical tooth surface or a drum surface.

Example 4

Fig. 2 shows a variable tooth worm according to a fourth embodiment of the present invention. The tooth surface indexing circular surface is a circular arc turning surface, and the tooth top surface is a drum shape. The center distance is a = 125mm, the speed ratio is i = 3/42, and the maximum outer diameter is E) 62mm.

The manufacturing steps of the variable gear worm are as follows: the blank of the shaft body 1 with the same shape as the finished product is firstly made into a spiral tooth 2 worm blank on a toroidal worm lathe according to the prior art; Worm grinders or other worm grinders are used for finishing, grinding and forming as required. It can also be made into a cylindrical surface. This embodiment is simple to manufacture and the obtained cylinder Surface or drum-shaped variable worms work well. Industrial applicability

Compared with the prior art, the technical solution of the present invention has the following advantages and effects:

1. In the transmission, since the number of teeth that are simultaneously meshed is larger than that of the cylindrical worm, and it is gradually entered and disengaged, the bearing capacity and transmission efficiency are significantly improved, and the transmission performance is more ideal;

2. In the transmission, the number of teeth and parts that mesh at the same time is less than that of the toroidal worm, with less heat generation, less oil stirring loss, and lower installation and adjustment requirements for the center distance and axial size. Corresponding box structure, oil capacity, oil temperature , Bearing life, etc. have been improved, easy to manufacture, and economical.

Claims

Rights request

1. A variable-worm worm is composed of a shaft body and spiral teeth thereon, characterized in that its tooth top surface is a cylindrical surface or a drum-shaped surface, and the index circle of the tooth surface is a curved surface of revolution.

2. The variable gear worm according to claim 1, wherein the index circle of the tooth surface is a circular arc turning surface.

3. The variable-worm worm according to claim 1, wherein the graduation circle of the tooth surface is an elliptical rotary surface.

4. The variable gear worm according to claim 1, wherein the index circle of the tooth surface is a parabolic revolution surface.

5. The variable gear worm according to claim 1, wherein the index circle of the tooth surface is a hyperbola revolution surface.