Valve Drilling Machine

Challenge: Design and build a machine that drills holes into the bottom of an aluminum valve stem body.

Solution: A bowl feeder with a vibratory inline conveyor queues the valve stems and positions the parts. A rotary table with eight positions indexes the stems from station to station. The table is divided into a dry zone and wet zone, to contain chips and coolant, and keep the components in the dry zone as clean and dry as possible. At the inline conveyor in the dry zone, the table indexes and grips the part while aligning a flat on the stem for proper drill alignment. The drill stations use standard length drill bits that are placed in the collet and bottomed out so the operator does not have to re-gauge each bit.

The first index takes the part into the wet zone, and stops at an automatically-fed drilling station. The coolant is misted onto the drill using an Acculube misting lubricator. The table cycles again once the drilling operation is complete, bringing the part to a second drill, where an optional second hole can be drilled. The operator can select single or dual-hole drilling modes from the HMI. After drilling, the machine indexes to a blow-off station to remove any chips and coolant left on the part. The part then indexes into the dry zone once again. Drill bit breakage detection is accomplished with a mechanical whisker sensor at each drill head.

The camera station detects out of tolerance or missing holes with a tolerance of +/- 0.001". This machine meets or exceeds a Cpk of 1.66, and has run 12-14 million parts.