CNC lathe machining high precision spur gear machining
The selection of references for gear positioning often differs depending on the structural shape of the gear. This shaft gear is mainly used for top positioning, and when the hole diameter is large, the cone is blocked. The accuracy of the highest positioning is high, and the benchmark can be unified.
1. Positioning criteria
The selection of references for gear positioning often differs depending on the structural shape of the gear. This shaft gear is mainly used for top positioning, and when the hole diameter is large, the cone is blocked. The accuracy of the highest positioning is high, and the benchmark can be unified. When machining the gear surface, the following two positioning and clamping methods are generally used for toothed gears.
(1) Positioning with the inner hole and the end face is about to
The inner hole and the end face of the workpiece are co-located to determine the center and axial position of the gear, and the clamping method facing the positioning end face is adopted. The method makes positioning reference, design basis, assembly reference and measurement reference coincide, has high positioning accuracy, and is suitable for mass production. However, the requirements for manufacturing precision fixtures are very high.
(2) Positioning of outer circle and end face
The matching gap between the workpiece and the clamping mandrel is large, and the outer circle is corrected with a dial indicator to determine the position of the center and locate the end face. Clamp from the other end. This method is calibrated for each workpiece, so the production efficiency is low; it requires high coaxiality of the inner and outer circles of the blank, but does not require high precision of the fixture, so it is suitable for single piece and small batch production.
2. Processing of gear blanks
The rough machining of the gear tooth surface before machining plays an important role in the whole gear machining process. Because it is necessary to process the datum for tooth surface machining and inspection at this stage; the machining of the gear blank must be emphasized regardless of the increase in productivity or the quality of the gear.
In the technical requirements of the gear, attention should be paid to the dimensional accuracy of the addendum circle. Since the tooth thickness is measured based on the addendum circle, the accuracy of the addendum circle is too low, which inevitably makes the measured tooth thickness value incorrect.
Therefore, the following three issues should be paid attention to in this process:
(1) When the diameter of the tip circle is used as a measurement reference, the dimensional accuracy of the tip circle should be strictly controlled.
(2) Ensure the perpendicularity between the positioning end face and the positioning hole or outer circle
(3) Improve the manufacturing accuracy of the gear inner hole and reduce the matching gap with the fixture mandrel