There are four basic stages in the manufacture of electronic connectors
There are many kinds of electronic connectors, but the manufacturing process is basically the same, generally divided into the following four stages:
Stamping (Stamping),
Plating (Plating),
Injection Molding (Molding),
Assembly (Assembly),
2.1 stamping
The manufacturing process for electronic connectors generally begins with stamping and inserting pins. Electronic connectors (pins) are punched out of thin metal strips by large high-speed presses. One end of the large coil of metal belt is sent to the front end of the punching machine, and the other end passes through the hydraulic table of the punching machine and is wound into the winding belt wheel, which pulls out the metal belt and rolls out the finished product.
2.2 plating
The connector should be sent to the electroplater immediately after stamping. At this stage, the electronic contact surfaces of the connector will be coated with various metal coatings. Problems similar to the stamping stage, such as twisting, cracking or deformation of the pins, also occur when the punched pins are fed into the electroplating equipment. This kind of quality defect can be easily detected by the technique described in this paper.
However, for the majority of machine vision system suppliers, many quality defects in electroplating are still in the "forbidden area" of detection system. The electronic connector manufacturer expects the inspection system to detect all kinds of inconsistencies on the connector pin plating surface, such as fine scratches and pinholes. Although these defects are easily recognized by other products, such as aluminum cans or other relatively flat surfaces; But because of the irregular and angular surface design of most electronic connectors, visual inspection systems have a hard time getting the images needed to recognize these subtle defects.
Because some types of pins need to be coated with multiple layers of metal, manufacturers also want the system to be able to distinguish between different metal coatings so that they are in place and in proportion. This is a difficult task for a visual system using a black and white camera, because the image shades of different metal coatings are virtually identical. Although the camera of the color vision system is able to distinguish these different metal coatings successfully, lighting difficulties remain due to the irregular angles and reflections of the coating surfaces.
2.3 injection
The plastic box holder for the electronic connector is made in the injection stage. The usual process involves injecting molten plastic into a metal matrix and then rapidly cooling it into shape. A so-called "leak" occurs when molten plastic does not fill the membrane completely. Quot; (Short Shots), which are typical defects to be detected during injection molding. Other defects include filling or partial blockage of the connecting jacks (which are kept clean and smooth so that they are properly connected to the pins during assembly). The machine vision system for quality inspection after injection molding is relatively simple and easy to implement because the backlight can easily identify the box seat leakage and socket plugging
2.4 the assembly
The stage of the manufacture of electronic connectors is the assembly of the finished product. There are two ways to connect the electroplated needle with the injection box seat: single pair or combined pair. Single pair insertion refers to one pin insertion at a time. The combined pair insertion is to connect multiple pins with the box seat at the same time. No matter which type of insertion is adopted, the manufacturer requires all insertion pins to be inspected for defects and correct positioning during the assembly stage. Another kind of routine detection task is related to the measurement of connector mating surface spacing.
As in the stamping stage, the assembly of connectors presents a challenge to the detection speed of the automatic detection system. Although most assembly lines take one to two pieces per second, the visual system usually needs to complete several different inspection items for each connector through the camera. So the detection speed becomes an important system performance index again.
After assembly, the outer dimensions of the connectors are much larger in quantity than the dimensional tolerances allowed for individual pins. This poses another problem for visual detection systems. For example, some connector boxes are over a foot in size and have hundreds of pins, each of which is within a few thousandths of an inch in size. Obviously, a one-foot-long connector can't be detected in one image, and the visual detection system can only detect a limited number of pin qualities in a small field of vision at a time. There are two ways to complete the detection of the whole connector: using multiple cameras (increasing system cost); Or the camera is continuously triggered when the connector passes in front of a lens, and the visual system "stitches" the single-frame image taken continuously to determine the quality of the entire connector. The latter method is usually adopted by PPT visual inspection system after connector assembly.
Detection of "True Position" is another requirement of connector assembly for detection system. This "actual position" is the distance between one end of each pin and a specified design reference line. The visual inspection system makes this imaginary reference line on the inspection image to measure the "actual position" of each pin point and determine whether it meets the quality standard. However, the reference points used to demarcate this reference line are often not visible on the actual connector, or sometimes appear on another plane and cannot be seen at the same time on the same lens. In some cases, plastic had to be ground away from the connector casing to determine the position of the reference line. A related issue does arise here - detectability design.
Trainability design (Inspectablity)
New machine vision systems are being used more and more widely due to the constant demands of manufacturers to improve production efficiency and quality and reduce production costs. As various visual systems become more common, people become more familiar with the characteristics of such detection systems and learn to consider the detectability of product quality when designing new products. For example, if you want a reference line to detect the "actual location," you should consider the visibility of that reference line in your connector design.