A new negative pressure approach for in-process 2D laser sensor measurement with coolant condition

The in-process optical measurement can provide precise and fast response measurement result to improve machining quality and efficiency. However, the coolant used during machining process would block the optical measurement path and prevent the measurement. Several existing coolant displacing approaches, which utilize air/water/coolant to resist incoming coolant, can help single point laser sensor conduct measurement with coolant condition. Nowadays, the 2D laser sensor is being used more frequently to increase measurement efficiency and to get real-time 3D workpiece profile. To help 2D laser senor to measure workpiece surface with coolant condition, this paper proposed a negative pressure approach. This approach utilizes the negative pressure to suck air/coolant away from measurement window. The experimental results show that the proposed approach can help 2D laser sensor conduct measurement on workpiece surface, even when the workpiece is submerged in coolant with a thickness of T c = 12 mm. For the measurement on workpiece with PV value of 151.2 μm, the relative uncertainty of 2σ is up to 0.71 %, where the standard deviation is up to 0.536 μm. The experimental results also show that, when compare the new proposed approach with existing coolant displacing approaches, the measurement window size could increase by 7.8 times, and the measurement efficiency could increase by 789 times. This study shows that the new negative pressure approach could help 2D laser sensor successfully conduct measurement with coolant condition, therefore it significantly improves the in-process optical measurement efficiency and makes it possible to get 3D workpiece profile in real-time with coolant condition.