What is the most basic parameter in the gear parameters

Advantages of gear transmission: 1) High transmission accuracy. As mentioned earlier, the belt drive cannot guarantee the accurate transmission ratio, and the chain drive cannot achieve a constant instantaneous transmission ratio, but the transmission ratio of the involute gear commonly used in modern times is accurate and constant in theory.

This is not only a key requirement for precision machinery and instruments, but also an important condition for reducing dynamic load and achieving smooth transmission under high speed and heavy load. 2) Wide scope of application. The power range of gear transmission is extremely wide, and it can be transmitted between any two shafts in space such as parallel shafts, intersecting shafts, and staggered shafts from 0 3) can be realized, which is also impossible to do with belt drive and chain drive.

4) Reliable work and long service life. 5) The transmission efficiency is higher, generally 0 6) The manufacturing and installation requirements are higher, so the cost is also higher. 7) Strict requirements for environmental conditions, except for a few low-speed, low-precision...

From the perspective of the parameters of a single gear, the most basic should be the modulus, the number of teeth, the pressure angle, the displacement coefficient, the tooth width, and the rest of the parameters can be deduced from these five parameters.

The essence is the base circle, the number of teeth, the root circle, the top of the tooth circle, the base circle tooth thickness, and the helical gear plus the helix angle of the base circle.

The above parameters will not change as long as the gear is determined.

Unlike modulus, pressure angle, displacement coefficient, etc., which are defined for easy calculation or standardization, it is completely possible to change another set of parameters to describe the same gear. It is not actually possible to measure directly or a reference (point) circle must be specified to measure.

The basic parameters of standard spur cylindrical gears: number of teeth, modulus, pressure angle, tooth top height coefficient; Top clearance coefficient.

The meanings are, in order: the number of teeth; the ratio of tooth pitch to ; the angle of pressure of the involute on the index circle; the ratio of the tooth top height to the modulus; The ratio of the radial clearance between the top of the tooth and the root of the tooth to the modulus.

Look at what kind of gear, the main parameter of the spur cylindrical gear is the number of teeth is the modulus.

1. Number of teeth z: refers to the total number of teeth of a gear.

2. Modulus M: Modulus M is a basic parameter that determines the size of the gear, refers to the ratio of the tooth pitch p and pi between the tooth profile on the same side of the adjacent two wheel teeth, the larger the gear modulus with the same number of teeth, its size is also large.

3. The diameter of the indexing circle d: refers to the circle whose diameter is the product of the modulus multiplied by the number of teeth, it does not actually exist in the gear, it is just a defined circle, but the tooth size of the gear is determined based on this circle, and the diameter of the indexing circle is the number of teeth Z * modulus m.

4. Pressure angle: The pressure angle is the parameter that determines the tooth shape of the gear. At the tangent point p of the two gear pitch circles, the acute angle sandwiched between the common normal of the two-tooth profile curve and the common tangent of the two-segment circle is called the pressure angle, also known as the meshing angle.

The carrying capacity of small pressure angular gears is smaller, and the carrying capacity of large pressure angular gears is larger, but the load is also relatively large.

5. Tooth height and tooth thickness: the height of the gear tooth is determined by the modulus m, the height of the whole tooth, the height of the tooth root, and the height of the tooth top, where the height of the tooth top is the height from the top of the tooth to the index line, and the height of the tooth root is the height from the root of the tooth to the index line. The reference for tooth thickness is half of the tooth pitch.

In the above parameters, modulus and the number of teeth are the most important parameters of the gear, usually in the case of the number of teeth unchanged, the larger the modulus, the larger the gear teeth, the stronger the ability to resist breaking, of course, the larger the gear billet, the larger the space size; Under the condition that the modulus remains unchanged, the larger the number of teeth, the smoother the involute, and the thickness of the round tooth at the top of the tooth and the round tooth thickness of the root are correspondingly thicker.

Commonly used gear types

1. Spur gear (spur gear).

Its teeth are parallel to the shaft and are used in a wide range of applications. Moreover, it is the easiest to manufacture.

2. Helical gear

3. Double helical gear (herringbone gear).

The double helix form balances the inherent thrust.

4. Crossed helical gear

As separate gear components, they are just conventional helical gears. They offer a simple way of gearing to accommodate any angle of inclination of the shaft. Because they are point contacts, they have a very limited carrying capacity.

5. Internal gear

This is a cylindrical gear, but there are teeth distributed inside the cylinder, and it can mesh with the spur gear. Internal gears are commonly used in planetary gear systems.

6. Spur rack

Spur gears that can mesh any number of teeth with gears. The straight rack is a part of a spur gear with an infinite radius.

The basic parameters of gears include modulus, number of teeth, pressure angle, indexing circle diameter, tooth width, center distance, tooth shape, and accuracy grade.

1.Modulus: The ratio of the number of gear teeth to the circumferential distance, usually denoted by "m".

2.Number of teeth: The number of teeth on the gear, usually denoted by "z".

3.Pressure angle: the angle between the gear tooth surface and the axis, usually indicated by "".

4.Indexing circle diameter: The diameter of the circle corresponding to the number of gear teeth, usually denoted by "d".

5.Tooth width: The width of the tooth surface of the gear is changed to slow rowing, usually indicated by "b".

6.Center Distance: When two gears mesh with each other, the distance between the center axis of the two gears, usually denoted by "a".

7.Tooth shape: The curve shape of the tooth surface of the gear, which can be described by a variety of curves, the most commonly used of which are arc and involute.

8.Accuracy class: The accuracy class of gear manufacturing, which is usually classified by the international standard ISO1328, includes 4 grades: 4, 5, 6 and 7.

A gear is a mechanical element with teeth on the rim that can continuously mesh to transmit motion and power. The application of gears in transmission has been around for a long time. At the end of the 19th century, the principle of the tooth cutting method and the special machine tools and tools that used this principle to cut the teeth appeared one after another, and with the development of production, the stability of gear operation was emphasized.

The development pattern of gears:

1. Gambling. Economic globalization and protectionism are in the stage of nuclear uproar. China's gears must mature in the competition.

The future competition pattern will be an obvious trend of collectivization, the focus of large international enterprises has shifted, they have increased investment in emerging markets such as China, and the internationalization of domestic competition has intensified; Foreign companies are paying more and more attention to Chinese elements, and will specialize in developing products for the Chinese market in the future.

2. Technological change.

Effective measures should be taken to transform and upgrade the gear industry with information technology, and change the situation of low grade and low economic benefits of gear products in China. Such as the use of automation, intelligent equipment, reduce costs and energy consumption; Promote the application of computer integrated manufacturing systems in the gear industry, and form a strong advanced equipment manufacturing system.

3. The general trend.

By the end of 2012, the annual sales revenue of the gear industry was about 160 billion yuan, with more than 1,000 production enterprises, more than 400 enterprises above designated size, and about 300,000 employees. After more than 20 years of unremitting efforts, China has become a gear power.

Pro, gear is a common mechanical element, and its basic parameters are as follows:1Number of teeth:

The number of gear teeth refers to the number of teeth on the hub, which is usually expressed by n. 2.Modulus:

Modulus refers to the ratio of the number of gear teeth n to the gear radius size r, which is usually expressed in m and the unit is millimeters. 3.Pressure Angle:

The pressure angle is the angle between the gear tooth profile and the gear shaft, which is usually expressed by . 4.Tooth width:

Tooth width refers to the width from the top of the gear tooth to the bottom of the tooth, usually expressed in b in millimeters. 5.Pitch:

Pitch refers to the distance between the top of two adjacent teeth, usually expressed in p, in millimeters. 6.Helix Angle:

The helix angle is the angle between the helix of the helical gear and the axis of the gear, which is usually expressed by . 7.Top Gap and Clearance:

Top clearance refers to the gap between the top of the gear tooth and the bottom of the rack tooth, and the clearance refers to the minimum gap between the gear and the rack. These basic slag lease parameters are important technical parameters that need to be considered in the design and manufacture of gears, and the performance and application range of gears can be reasonably determined by controlling and adjusting these parameters.