Automatic Piston Gage
Gage Parameters
The Challenge
The Solution The next stations incorporate a part rinsing and drying system. At the rinsing station, coolant is removed from the piston in a tank with nozzles located on the ID and OD of the part. A remote pump applies pressure through the nozzles. A retractable cover is on the tank to prevent splashing of the rinse. The drying station is similarly designed, but with compressed air pushing through the nozzles. Further, vacuum devices attract the water droplets out of the air that were blown off the part. The subsequent operation conducts an eddy current crack detection test while the part rotates 360¡. If no cracks .005 inch or larger are detected on the head and at several land diameters, the part moves on to a pinbore orientation area. A laser determines by reflection whether the part is aligned properly or not by the pinbore location. If not, the programmable logic controller interprets that the part is 180º off, and directs the part to be rotated into the correct position for gaging. The part is then conveyed to a roller burnishing station to impart a smooth surface finish. From there, the part is presented to a gage nest where three ODs are measured along with the concentricity of the skirt diameter to the oil ring groove. The measurements are accomplished via LVDT heads with pneumatic retraction for part loading. The pinbore is then air gaged in four places to check variances in taper and roundness at both ends. Compression height and pinbore offset measurements are also taken. All of the measurement data is fed into the CAG microprocessor for acceptance or rejection. The part is then sent to a scale for weighing, and passed on to a dot peen marking station. Then it travels to the sorter where the piston is categorized as "good" or "reject" on the basis of part status as determined by the CAG. Good parts exit from the gage; reject parts are transferred to a reject chute. The Result With the automatic piston gage, the company is getting 100% of its parts measured and sorted to ensure no reject parts are shipped. Statistical information from the CAG microprocessor is analyzed to make adjustments in the machining process, reducing the total number of reject parts produced.
Operations Performed
Skirt profile @ 2 places Concentricity or ring groove to skirt Pinbore diameter @ 4 places Pinbore taper Pinbore roundness Pinbore offset Compression height Detect Cracks Weigh Mark |
An automotive manufacturer's system of manually gaging its range of pistons during final inspection was slow, cumbersome, and did not provide 100% quality control. The company wanted an efficient method to measure each piston after machining, sort the good parts from the bad, and gather data that would provide information to improve their process.
Chip removal from ring grooves