Is it necessary to use precision gear rack? Many people have such doubts, and this article explains this problem. Precision rack and pinion are very necessary in many applications, especially in motion control systems that require high precision and high reliability.
1. Composition of Precision Gear Racks
Racks are parts similar to gears, but they do not have a hub, but have a raised part that engages with the gear. Racks are usually used to cooperate with gears for power transmission so that the equipment can operate normally.
Raised part: A raised part with a specific shape and size on the rack that is used to engage with the gear.
Smooth part: The rest of the rack is smooth to provide stable support in linear motion.
In mechanical equipment, racks are usually used to achieve linear motion or change the direction of motion. By cooperating with gears, racks can convert rotary motion into linear motion, or convert linear motion into rotary motion.
2. Advantages of High Precision Gear Rack
2.1 High Precision
In many industrial applications, such as CNC machine tools, laser cutting and robotics, accurate linear motion is critical. Precision rack and pinion can provide high-precision positioning and repeatability to ensure product quality and processing accuracy.
2.2 High Load Capacity
Precision gear racks can withstand large axial forces, radial forces and torques, and are suitable for various heavy-duty occasions. They are generally made of high-strength materials, have good wear resistance and fatigue resistance, and can operate stably for a long time in harsh working environments.
2.3 Fast Speed
Compared with other transmission methods, gear rack modules can achieve higher movement speeds, up to several meters per second or even higher. This makes it widely used in some automated production lines with high production efficiency requirements.
2.4 Adaptability and Flexibility
High precision gear racks can be customized according to the needs of specific applications to meet different motion control requirements. For example, by splicing racks, a longer stroke can be obtained, which is a significant advantage of gear rack long-stroke applications.
2.5 Low Maintenance Cost
The working principle of gear rack transmission is simple and reliable, with a low failure rate, which reduces the time and cost of equipment downtime maintenance. Daily maintenance mainly includes regular cleaning, lubrication and inspection of gear rack wear, etc. The maintenance work is relatively simple and does not require professional technicians to operate.
3. Main Features of Precision Gear Racks
- Since the rack tooth profile is a straight line, each point on the tooth profile has the same pressure angle, which is equal to the inclination angle of the tooth profile. This angle is called the tooth profile angle, and the standard value is 20°.
- Any straight line parallel to the tooth top line has the same pitch and module.
- A straight line parallel to the tooth top line and with a tooth thickness equal to the tooth width is called a dividing line (center line), which is the reference line for calculating the rack size.
- The main function of high precision gear racks in mechanical equipment is to transfer power from one place to another. When a gear or rack rotates, they will drive another gear or rack that is meshed with it to rotate together.
4. Precautions
For high precision gear rack transmissions that start transmission and have impact loads, there are several aspects to pay attention to:
- It is best to design it as a displacement gear, and a negative displacement gear. Negative displacement will help improve the bending strength of the tooth root and help improve the impact resistance of the gear.
- The heat treatment hardness of the tooth surface should not be too hard, HRC30~HRC35 is enough. Too hard tooth surface will cause gear cracking under impact load.
- The quenching depth of the tooth surface should not be too deep, generally 1/5m~1/10m (m: modulus), to keep the core material with sufficient toughness to buffer the external impact load.
- Under the premise that the structure allows, the modulus m should be slightly larger, which is especially important for the initial transmission with impact load.
- The design speed should not be too high.
- The structure should have sufficient impact resistance and sufficient rigidity to ensure the operation of the high precision gear rack.
- It is recommended to choose sliding bearings instead of rolling bearings. Sliding bearings can have good impact resistance, but it is necessary to ensure that the sliding bearings have good lubrication.
Summary
In many applications that require high precision, high load capacity and fast response, the use of gear racks is very necessary. They not only improve the performance and reliability of the system, but also promote the development of industrial automation and intelligent manufacturing. Therefore, it is a wise choice to consider the use of precision gear racks when designing and selecting motion control systems.
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