In the field of modern automobile manufacturing, the thread of components is the most basic, widely used, and standardized connection technology in the automobile assembly process. The reliability of the thread connection structure is related to the overall performance of the automobile, especially the high-strength thread connection structure of the chassis and other parts, which is also related to the driving safety of the automobile.

In this issue, Xiao Ming will share Meiji Sensing's machine vision sensor solution for thread detection on car chassis covers~

Project Requirements

In this project, we want to use visual sensors to measure the presence of internal threads in screw holes on product components and whether the end surfaces of the holes have been cut and polished.

Require the ability to accurately detect whether there are threads in the screw holes of product components; Accurately identify whether there are threads in the screw hole. If there are threads, execute the OK signal and the product enters the next process for inspection; If there are no threads or openings in the screw hole, output an alarm signal to the mechanical actuator to remove defective products.

Key points analysis

1. Front height difference hole detection/cutting inspection

The detection at this workstation involves a camera simultaneously detecting two holes, and there is a height difference of about 5cm and a significant difference in hole size between the two holes. Depth of field needs to be considered when imaging.

2. Side single convex hole detection

Single hole detection, with larger dimensions

Two holes with significant deviation in side angle

The two holes protrude in two directions, and the size difference of the holes is not significant.

Introduction to Testing Scheme

Using the Meiji VG-BR050-DA12 visual sensor solution, 20000 products were tested and tested with zero abnormalities; It has been officially put into use in large quantities.

1. Cutting detection station for the front face

The light source should be facing the workpiece, and the camera light source and workpiece should be kept as perpendicular as possible.

Installation structure diagram of visual sensor

2. Single hole detection and detection stations with different directions for two holes

Installation distance is 200 meters; 20mm， The installation angle (high angle) between the camera and the workpiece needs to be determined based on the actual installation position. Hole detection with segment difference, installation distance at 270± 20mm， The installation angle between the camera and the workpiece needs to be determined based on the actual installation position

Installation structure diagram of visual sensor

   Visual sensor imaging effect    

 ✔ OK 

High and low segment difference hole (threaded)

❌ NG

High and low segment difference hole (without threads)

✔ OK

Two holes with significant angle difference (threaded)

✔ OK

Single raised hole on the side (threaded)

✔  OK, the red box indicates that it has been cut

❌  NG yellow box indicates no cutting