ll Bearing Vision System (BBVS) for Ball Bearing Assembly Machines

BALL BEARING VISION SYSTEM (BBVS) FOR BALL BEARING ASSEMBLY MACHINES

The system is designed to allow the end user to quickly and economically implement a ball presence/absence detection feature on a ball bearing assembly machine. The system is provided with the hardware components and application software required to implement the detection feature. The user needs only to supply the necessary bracketry to mount the components. The camera, lens, and fiber optic ring light are provided, mounted to an extruded aluminum column. Each component can be independently positioned at any point along the column. The optical center to the column center is set at eight inches. The electronics cabinet consists of an industrialized, Pentium-based processing platform, CRT, keyboard, camera, digitizer, and OPTO-22 modules to interface to the customer’s PLC.

The applications software has been developed from a library of routines which have been utilized over a number of years to provide specific presence/absence detection capabilities for turnkey full custom systems produced by IISD. The highest performance and most robust routines have been integrated into this package. A user-friendly interface has also been provided to allow a customer to quickly implement his specific ball detection application.

FEATURES
Digital focus setting aid
Live image display for positioning aid
User settable region of interest (ROI) set as the region between an outer and inner circle (annular ring)
Complete PLC handshaking
User Set Parameters
Number of Balls in Assembly
Pixel Threshold
Cluster High Size
Cluster Low Size
Width of Final Annular Ring to be Processed
Group Center to Ball to Adjacent Ball Angle

Image Processing

Clusters are formed by searching the ROI for pixels exceeding the pixel threshold. Clusters are formed even if they cross the ROI boundaries. The cluster sizes and centers are calculated. The clusters are compared to the size thresholds and eliminated if outside of the preset size. The centers of the remaining clusters are averaged and the group center for all of the clusters as well as an average radius are determined. The preset width of the final annular ring about this radius forms the final region for counting clusters.

All clusters with centers within this region are counted and compared to the assembly preset number of balls. An accept/reject condition is determined. A new group center for the counted clusters is calculated

The angle formed by the line which passes through the groups center and a cluster center and through that cluster center and an adjacent cluster center is compared to the preset angle limit. This is performed for all adjacent clusters in sequence and an accept/reject condition set. This is useful in detecting balls that are stacked on top of each other.

The OPTO-22 modules interface a “Part Ready” input from the machine PLC and output a “Processing complete” and “Part Accept” signal to the machine PLC for implementing completely automatic operation.

If the user has a unique bearing configuration, AIM can supply custom lighting specific to the user’s product to enhance the image for processing at a minimal charge. Evaluations of such configurations are performed by AIM, at our factory, free of charge.