Before milling, the path and cutting parameters of the milling cutter should be accurately set according to the mold design drawings. Use a high-precision CNC milling machine with a positioning accuracy of ±0.005mm or even higher to ensure that the milling cutter can move accurately along the preset trajectory. For tooth profile milling, select the appropriate milling cutter specifications according to the gear module and number of teeth. For example, the use of carbide coated milling cutters can not only ensure the sharpness of the cutting edge, but also reduce the impact of tool wear on dimensional accuracy.
Real-time monitoring of cutting force and temperature during milling, and feedback of data through sensors installed on the milling cutter handle or workbench. Once the cutting force is too large or the temperature rises abnormally, the workpiece may be deformed. At this time, the cutting parameters should be adjusted in time, such as reducing the feed speed and increasing the cutting fluid flow rate, to ensure that the mold is dimensionally stable during milling, and to control the key dimensional tolerance within a very small range. The general tooth profile dimensional tolerance can be controlled within ±0.01mm.
EDM has unique advantages for the fine structure and complex tooth profile of plastic gear mold. First of all, accurate electrode production is the key. The shape and size of the electrode should be designed according to the reverse design of the mold cavity. High-precision equipment is also used when processing the electrode to ensure that the electrode size accuracy is one level higher than the plastic gear mold requirement. For example, the mold size tolerance requirement is ±0.02mm, and the electrode tolerance is controlled at ±0.01mm.
During the EDM process, the discharge parameters are optimized, including pulse width, pulse interval, discharge current, etc. Fine adjustment of these parameters can control the discharge erosion amount and avoid excessive or insufficient processing. Using the adaptive control system of the advanced EDM machine tool, the discharge gap is monitored in real time, and the parameters are automatically adjusted according to the gap change to ensure that the key size tolerance of the mold is stable when processing deep grooves, narrow slits and other parts. For example, the cavity depth tolerance can be controlled within ±0.02mm to meet the high-precision requirements of the plastic gear mold.
After milling and EDM are completed, high-precision detection equipment is used for measurement immediately. The three-dimensional coordinate measuring machine can comprehensively detect the three-dimensional dimensions of the plastic gear mold, obtain detailed data and compare it with the design model. If critical dimensional deviations are found, micro-grinding corrections are performed on precision grinders for the milling out-of-tolerance parts; if there are EDM errors, local trimming is performed again through EDM with small current and short pulses to ensure that the final dimensional tolerance of the mold meets the high-precision requirements of plastic gear molding, thereby ensuring product quality and performance.
