1. Field of the Invention
This invention relates generally to enlarging or finishing a workpiece bore hole and more specifically to a system and method for ballizing and measuring a workpiece bore hole.
2. Description of the Background Art
When machining a bore hole into a workpiece, one typically uses a boring machine to turn the initial bore hole. The level of precision of the bore hole dimensions (e.g., the bore hole diameter) usually relates to the level of precision of the turning process. In high precision applications, one may perform a ballizing process to enlarge the machined bore hole and/or to finish the machined bore hole to increase the accuracy of the bore hole dimensions and to provide a good surface finish. In such a process, a machine pushes a ball having a diameter that is known with a very high degree of precision through the machined bore hole. The force that the ball exerts on the workpiece as it traverses the length of the bore hole shapes the bore hole.
One drawback of the above approach to machining bore holes is that a bore machine usually is not able to produce the high quality bore form and accurate bore hole dimensions necessary for high precision applications. Another drawback is that current ballizing processes require that after a given ball is pushed through the workpiece bore hole the workpiece must be removed from the ballizing machine to be measured. Measuring typically entails cleaning the workpiece to the standards of a metrology laboratory and then sending the cleaned workpiece to the metrology laboratory for measuring. This process is time consuming and expensive. Yet another drawback is that current ballizing machines oftentimes do not have efficient ways to return the ball to the upper side of the workpiece once the machine has pushed the ball through the length of the workpiece bore hole.