Screw Milling Machine CNC Transformation
Injection molding machines and extruders are specialized equipment used in the production of plastic products, and they are widely utilized around the globe. As a critical component of both extruders and injection molding machines, the quality of the screw directly influences the performance of these systems. Traditional manual methods for machining screws often result in inconsistency, low efficiency, and unreliable quality. To address these challenges, the application of numerical control (NC) technology in screw processing has become an inevitable trend.
Currently, dedicated CNC screw milling machines are costly and not easily adopted by many users. On the other hand, economical CNC screw milling machines derived from lathes using basic numerical control systems and stepper motors offer limited functionality and tend to be less reliable, leading to frequent issues during operation.
Nanjing Sikai Electronic Enterprise Co., Ltd. responded to a customer request from Guangdong by installing the SKY CNC system on a lathe, successfully transforming it into a specialized CNC screw milling machine. This system offers cost-effectiveness, enhanced functionality, improved ergonomics, high precision, and excellent uniformity in the machined screws. It is capable of handling various special requirements such as variable diameter, variable pitch, and even continuous or segmented variable pitch screws.
The system features a user-friendly Chinese interface, full-screen program editing, and a large memory capacity that can store up to 10,000 machining programs reliably. The machine tool is driven by digital AC servo motors with sufficient power margins, ensuring high stability and reliability. This solution effectively addresses common challenges in screw machining.
The SKY CNC screw milling machine was developed by modifying a standard lathe, as shown in Figure 1. The basic structure includes a digital AC servo motor for the spindle (A), X-axis and Z-axis digital AC servo motors, the workpiece, the milling spindle, and the top. The machine is equipped with milling heads on the lathe carriages, allowing three-axis linkage control to produce complex screw shapes.
The traditional lathe tool holder was removed and replaced with a milling head. The milling head and spindle are driven by the digital AC servo motor via timing pulleys and belts, while the X and Z axes are connected directly to ball screws through couplings. This design simplifies the mechanical structure, enhances flexibility, and reduces transmission errors.
The SKY CNC system uses an encoder mounted on the motor as a feedback element, paired with a digital AC servo motor to create a closed-loop system. The high-resolution encoder provides digital pulse feedback, and the servo system employs dual-pulse input control to improve anti-jamming capabilities. The system supports both full closed-loop and semi-closed-loop configurations based on user needs.
Built on a universal PC platform, the SKY CNC system allows for custom programming using C language for specific screw machining tasks. A built-in parameter programming module facilitates easy operation, as illustrated in Figure 2. By inputting different screw parameters, corresponding equations can be established to generate precise machining instructions.
Depending on the required screw accuracy, an appropriate increment "dt" is calculated, and the corresponding spatial coordinates (X, Z, A) are output according to the NC code. Through this CNC transformation, significant improvements in accuracy and consistency have been achieved, leading to substantial social and economic benefits.
With numerous conventional screw milling machines currently in use across the country, the potential for CNC retrofitting is vast, offering a promising future for the industry.
Multi Wedge Belt,V Ribbed Belt,Multi-Wedge Rubber Belt,Industrial Multi Wedge Belts
Jiangsu Bailite Transmission Technology Co., Ltd , https://www.zsindustrialbelt.com