CNC technology provides higher precision, efficiency and automation for the processing of rack and gear, which can meet the needs of modern manufacturing industry for high-quality gear parts. The following will discuss how to choose the appropriate CNC processing method according to different processing requirements.
The processing of CNC rack and pinions are as follows: milling, broaching, grinding, gear shaping, and heat treatment.
Milling Gear
The milling of racks is generally processed by ordinary milling machines, and there are also special milling equipment. The rack is hydraulically clamped after positioning in the jaws of the clamp, and the forming hob (or milling cutter) is installed on the main shaft of the equipment and rotates. The servo motor drives the whole milling of the CNC rack and pinion. During the milling process, a large amount of cooling oil flushes the milling area, cools the workpiece and the hob, and washes away a large amount of iron filings. The hob rises to the end of the stroke and then quickly returns to the starting point. The cooling oil is turned off, and then the fixture is loosened, the rack is taken out, and the second rack is installed to enter the next cycle.
The overall milling gear processing combines many advantages such as high dimensional accuracy, good tooth surface finish, and good dimensional stability. It is widely used in multi-variety small batch production.
Gear Broaching Process
On the broaching machine, the rack is hydraulically clamped after being positioned in the jaws of the clamping body. The broaching tool is installed on the broaching tool base. Driven by a hydraulic cylinder or a high-power servo motor, the broaching tool broaches the CNC rack and pinion. During the broaching process, a large amount of cooling oil flushes the broaching area, which not only cools the workpiece and the broaching tool, but also washes away a large amount of iron filings. After the broaching tool reaches the end of the stroke, it sends a signal, the clamp is released, the rack is removed, the broaching tool quickly returns to the starting point, the cooling oil is turned off, and the second rack is installed to enter the next processing cycle.
Gear broaching has many advantages such as high production efficiency, high dimensional accuracy, good dimensional stability, and good economy. It is widely used in mass production.
Grinding Process
Grinding often uses a dedicated rack grinder. The rack is cut on the grinder to remove excess metal and improve the surface accuracy of the CNC rack and pinion. Grinding is usually used for racks and gears with high precision requirements, especially when the rack surface requires high hardness or finish.
Grinding is mainly used for precision machining of racks, such as high-demand transmission parts or equipment that requires high tooth surface accuracy.
Gear Shaping
Gear shaping is a method of forming a tooth shape by cutting along the length of the rack with a gear shaping tool. This method is suitable for small-batch production or customized rack processing.
The gear shaping process uses a gear shaping tool, and the processing process is relatively slow. Usually, this method is used to manufacture racks with special tooth shapes. It is suitable for more complex tooth shape processing, especially for single-piece small-batch production.
Heat Treatment
There are two methods for heat treatment of CNC rack and pinions:
1. Quenching treatment: heat treatment done on the tooth surface after the rack is machined and formed. Generally, the hardness of the tooth part is above HRC50, and the hardness varies depending on the material used.
2. Quenching and tempering treatment: a heat treatment method done on the rack before processing, with an overall hardness of HRC20-25.
The material undergoes carbon diffusion on the surface at high temperature and then quenching. This increases the surface hardness and reduces the wear effect, thereby increasing the maximum allowable load and durability of the product.
Summary
When choosing the appropriate processing method, factors such as the material, batch requirements and precision requirements of the CNC rack and pinion should be considered comprehensively. Understanding the basic principles and application areas of these processing technologies is very important for designing and manufacturing high-performance gear systems.
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