Tubesheet Deep Hole Machining Accuracy Control

Tubesheet deep hole machining uses carbide step drills with a spindle speed of 800-1200rpm and a feed rate of 0.05-0.1mm/r, which can guarantee a hole diameter tolerance of ±0.02mm. Chip removal and cooling are required every 50mm of machining to prevent drill runout from causing straightness deviations (required ≤0.1mm/m).

Introducing gun drilling technology with high-pressure cutting fluid (8-12MPa) can achieve a surface roughness of Ra1.6μm. Using an online diameter measuring instrument for real-time compensation can control the cumulative hole spacing error within ±0.05mm.

After machining, a coordinate measuring machine (CMM) is required for inspection, focusing on monitoring the perpendicularity (≤0.03mm) and position (Φ0.1mm) of the tube holes. For titanium composite tubesheets, material stress relief treatment is required beforehand.