Types of gears: structure, function and application
Gears are one of the most common components in mechanical transmission and are widely used in various mechanical equipment to transmit power, change speed and direction. There are many types of gears, each with its own unique structure and function, suitable for different application scenarios. This article will introduce the common types of gears in detail, including their structural characteristics, working principles, processing technology and applications in different fields.
Basic principles and classification of gears
Basic principles of gears
Gears are mechanical elements that transmit power and motion through the meshing of gear teeth. Its working principle is based on the meshing of the teeth of two gears, which transmit torque and motion through the contact force of the tooth surfaces. Gear transmission has the characteristics of high efficiency, high precision and high reliability, and is widely used in various mechanical systems.
Classification of gears
Gears can be classified in many ways according to their structure, shape, purpose and processing method. Common classification methods include:
Classification by gear shape:
- Cylindrical gear
- Bevel gear
- Worm gear
- Non-circular gear
Classification by gear meshing method:
- External meshing gear
- Internal meshing gear
- Gear and rack
Classification by gear transmission direction:
- Parallel axis gear transmission
- Intersecting axis gear transmission
- Staggered axis gear transmission
Classification by gear accuracy level:
- Precision gear
- Ordinary gear
- Low-precision gear
Common gear types and their characteristics
Cylindrical gears
Cylindrical gears are the most common type of gears, with tooth profiles distributed on a cylindrical surface, suitable for transmission between parallel shafts.
Structural features:
- The tooth profile of the gear is usually involute shape, with good meshing performance and load-bearing capacity.
- It can be designed as straight teeth, helical teeth or herringbone teeth to meet different transmission requirements.
Type:
- Spur gear: The tooth line is parallel to the axis, the structure is simple, and the processing is convenient, but axial force will be generated during transmission.
- Helical gear: The tooth line is at a certain angle to the axis, the transmission is stable, and the load-bearing capacity is high, but the balance of axial force needs to be considered.
- Herringbone gear: It is composed of left and right helical teeth, which can automatically balance the axial force and is suitable for high-power transmission.
Application areas:
- Widely used in mechanical transmission systems, such as automobile transmissions, industrial reducers, motors, etc.
Bevel gears
Bevel gears have tooth profiles distributed on a conical surface and are suitable for transmission between intersecting shafts.
Structural features:
- The tooth profile of the gear is usually involute or arc tooth shape, which can realize the transmission of two intersecting axes.
- Axial force will be generated during transmission, which needs to be supported by bearings.
Type:
- Spur bevel gear: The tooth line intersects with the axis, the structure is simple, but the transmission noise is large.
- Spiral bevel gear: The tooth line is arc-shaped, the transmission is smooth, the noise is low, and the load capacity is high.
- Spiral bevel gear: The tooth line is spiral, the transmission efficiency is high, and it is suitable for high-precision transmission.
Application areas:
- Commonly used in automobile differentials, mechanical steering systems, machine tool spindle drives, etc.
Worm Gear
Worm gear is a special form of gear transmission, consisting of a worm and a worm wheel, suitable for transmission between staggered shafts.
Structural features:
- The worm is similar to a thread, and the worm wheel is similar to a helical cylindrical gear, and the two are meshed through helical teeth.
- The transmission ratio is large and the structure is compact, but the transmission efficiency is low, and it is usually used for reduction transmission.
Type:
- Ordinary worm gear: suitable for general reduction transmission.
- Helical worm gear: more stable transmission and higher load-bearing capacity.
- Circular arc tooth worm gear: the tooth surface is arc-shaped, with high transmission efficiency, suitable for high-precision transmission.
Application areas:
- Widely used in lifting machinery, reducers, machine tool feed mechanisms, etc.
Non-circular gears
Non-circular gears have tooth profiles that are not standard circles and are used to achieve special transmission requirements.
Structural features:
- The tooth profile of the gear is designed according to specific transmission requirements and can be non-circular, elliptical or other complex shapes.
- The transmission ratio changes over time and is suitable for occasions where variable speed transmission is required.
Types:
- Elliptical gears: used to achieve periodic variable speed transmission.
- Hyperbolic gears: used to achieve high-precision transmission.
- Variable tooth thickness gears: used to achieve non-uniform transmission.
Application fields:
- Commonly used in robot joints, precision instruments, aerospace and other fields.
Gear Processing Technology
Basic methods of gear processing
There are many different methods for gear processing. Different processing techniques can be selected according to the type and precision requirements of the gear. Common processing methods include:
Gear hobbing:
- Gear hobbing cuts are used to cut the tooth shape on the workpiece. It is suitable for processing spur, helical and herringbone cylindrical gears.
- It has high processing efficiency and precision, and is one of the most commonly used gear processing methods.
Gear shaping:
- Gear shaping cuts are used to cut the tooth shape on the workpiece. It is suitable for processing internal gears and multi-link gears.
- It has high processing precision but relatively low efficiency.
Gear milling:
- Gear shape is cut on the workpiece by milling cutters. It is suitable for processing small batches of gears or gears with complex shapes.
- It has low processing precision but high flexibility.
Gear grinding:
- Gears are ground by grinding wheels to improve the precision and surface quality of gears.
- It is suitable for processing high-precision gears, such as automotive transmission gears and aerospace gears.
Modern gear processing technology
With the continuous advancement of technology, modern gear processing technology is also constantly developing to meet the needs of high precision, high efficiency and complex shape processing.
- High-precision gear machining is achieved through CNC machine tools, which can produce complex tooth shapes and high-precision gears.
- CNC machining technology combines multiple processes such as gear hobbing, gear shaping and gear grinding to improve machining efficiency and precision.
Precision forging:
- Gear blanks are manufactured through precision forging technology, which reduces machining allowances and improves material utilization.
- It is suitable for mass production and can significantly reduce production costs.
Powder metallurgy:
- Gears are manufactured through powder metallurgy technology, which has the characteristics of high precision, high strength and light weight.
- It is suitable for the manufacture of small-sized, high-precision gears, such as micro gears and precision instrument gears.
Application areas of gears
Automotive Industry
Gears are widely used in the automotive industry, covering almost all transmission systems of automobiles.
Transmission gear:
- Used in automobile transmission to achieve power transmission at different speeds.
- Requires high precision, high load capacity and good wear resistance.
Differential gear:
- Used in automobile differential to achieve differential transmission of wheels.
- Usually uses bevel gears, requiring high precision and high reliability.
Steering system gear:
- Used in automobile steering system to achieve transmission of steering mechanism.
- Requires high precision and low noise, usually uses helical cylindrical gears.
Aerospace field
The aerospace field has extremely high requirements for gears, requiring high precision, high strength and lightweight design.
Engine gears:
- Used in aircraft engines to achieve power transmission and speed regulation.
- Usually made of high-strength alloy steel or titanium alloy, and undergo precision machining and heat treatment.
Flight control system gears:
- Used in the transmission mechanism of the flight control system to achieve high-precision control.
- Requires high precision, high reliability and good fatigue resistance.
Landing gear gears:
- Used in the retracting and extending mechanism of the landing gear to achieve the extension and rotation of the landing gear.
- Requires high strength and high reliability, usually uses bevel gears or worm gears.
Industrial Machinery
Gears are also widely used in industrial machinery, for various transmission systems and automation equipment.
Reducer gears:
- Used in industrial reducers to achieve high reduction ratios and high torque transmission.
- Requires high load capacity and good wear resistance, usually uses helical cylindrical gears or herringbone cylindrical gears.
Machine tool gears:
- Used in the spindle transmission and feed mechanism of machine tools to achieve high-precision processing.
- Requires high precision and low noise, usually uses precision grinding.
Robot joint gears:
- Used in the transmission mechanism of robot joints to achieve high-precision motion control.
- Requires high precision, high reliability and good fatigue resistance, usually uses non-circular gears or harmonic gears.
Medical equipment
Gears also have important applications in medical equipment and are used in the transmission systems of various precision instruments and equipment.
Medical equipment gears:
- Used in the transmission mechanism of medical equipment to achieve high-precision control.
- Requires high precision, high reliability and good corrosion resistance, usually made of stainless steel or aluminum alloy.
Diagnostic equipment gears:
- Used in the transmission system of diagnostic equipment to achieve high-precision movement.
- Requires high precision and low noise, usually precision grinding.
Rehabilitation equipment gears:
- Used in the transmission mechanism of rehabilitation equipment to achieve high-precision motion control.
- Requires high precision, high reliability and good fatigue resistance, usually non-circular gears or harmonic gears.
Future development trend of gears
High-precision and high-efficiency processing
With the continuous advancement of technology, gear processing will develop in the direction of high precision and high efficiency. Modern processing technologies such as CNC processing technology, precision forging technology and powder metallurgy technology will be more widely used to meet the needs of high-precision, high-efficiency and complex shape processing.
Lightweight and high-performance materials
In the fields of aerospace and automobiles, lightweight design is an important trend in the future. High-performance materials such as high-strength aluminum alloys, titanium alloys and composite materials will be more widely used to achieve lightweight and high-performance gears.
Intelligence and automation
Intelligence and automation are important development directions for future gear manufacturing. By introducing industrial Internet, big data and artificial intelligence technologies, the gear manufacturing process will be automated and intelligent. For example, intelligent CNC machine tools can automatically adjust processing parameters according to processing data to improve processing efficiency and quality.
Green manufacturing
Green manufacturing is an important development direction for the future manufacturing industry, and gear manufacturing is no exception. Gear manufacturing will achieve sustainable development by optimizing processing technology, reducing material waste and reducing energy consumption. For example, the use of efficient cutting tools and optimized processing procedures can reduce cutting time and reduce energy consumption. At the same time, recycling and reusing waste generated during processing can also reduce environmental pollution.
Conclusion
Gears, as the core components of mechanical transmission, have a wide range of applications and important roles. This article introduces in detail the types, structural characteristics, processing technology and applications of gears in different fields. With the continuous advancement of technology, gear manufacturing will develop in the direction of high precision, high efficiency, lightweight, intelligent and green manufacturing, providing strong support for the progress of the machinery manufacturing industry.