AC/DC Socket Bushing Automatic Assembly Line

Project scope

We designed an automatic EV charging power-component assembly line for AC/DC charging-socket bushing assemblies. The line is divided into a front section for resistor, thermistor and plastic-housing assembly, and a rear section for assembly, laser welding, testing and tray unloading. That makes the scope a Bushing Automatic Assembly Line application for socket bushing, thermistor, resistor assembly and laser welding.

The machine concept uses two eight-station ring-type magnetic levitation transport loops, four-axis robots, two CCD systems, solder-paste dispensing with height detection, two three-axis laser welding modules, resistance testing, CCD appearance inspection, nonstop tray loading and NG removal.

Coordinating two product variants

The equipment has to support both DC and AC charging-socket versions. The DC version includes one more resistor than the AC version, so the DC flow uses an additional resistor feeding and transfer mechanism. The AC flow removes that resistor feeding and handling section while keeping the rest of the assembly, welding, testing and tray handling route aligned.

Dedicated fixtures and controlled incoming tolerances

The technical notes define the machine as dedicated-purpose. If the assembled product changes, all fixtures and grippers need to be replaced. Incoming dimensions also need to stay within the corresponding tolerances, so the automation plan depends on controlled part geometry rather than trying to absorb large variation at the machine.

Module architecture

The line is organized around front-end component preparation and rear-end welding/test handling. The front section includes taped thermistor forming and feeding, plastic-housing vibratory feeding, resistor carrying and loading, resistor lead cutting and loading, resistor assembly, assembly-position detection and NG rejection. The rear section includes two three-axis laser welding modules, solder-paste dispensing with laser height measurement, resistance testing with a standard-sample station, CCD weld appearance inspection, nonstop tray loading and a four-axis pickup plus NG rejection module.

Front-end assembly

The taped thermistor forming and feeding module includes a tape reel shaft, stepping cut-and-feed unit, lead-cutting mechanism, left/right forming pushers, front pusher, PPU feeding, four-axis pickup, Y-axis transfer and lift/shift slides, plus an NG waste-tape bucket. Plastic housings are fed by vibratory bowl, straight vibration rail and separation module, then picked by a shaped suction nozzle.

The resistor assembly station uses a material-pushing cylinder, plastic-housing support rod, pin-foot probe and base. The eight-station magnetic-loop section uses moving platforms, ring rails, fixture tables and secondary positioning structures to carry parts through the front assembly route.

Welding, testing and unloading

The four-axis assembly robot uses a shaped assembly suction nozzle and pressure sensor. The solder-paste module uses a high-precision three-axis module, solder-paste valve, dispensing needle and laser height sensor. Welding is handled by two three-axis laser welding modules; the validation note lists a 3-second single-point weld and six weld points using two laser systems.

After welding and cooling, the rear section performs resistance testing and CCD appearance inspection. The test module includes appearance-detection CCD, test probes, cooling fan and standard-sample placement table. The tray handling module provides nonstop tray loading and unloading with separate waiting tray warehouse, finished tray warehouse, working bay and lifting component. A four-axis pickup and NG rejection module handles X/Y/Z/R movement, alternating grippers, CCD appearance inspection and NG box placement.

Variant handling and control package

For the DC charging-socket route, the process includes thermistor feeding, plastic-housing feeding, base pickup, push-in assembly, pressure-monitored four-axis installation, solder-paste dispensing with height check, two laser welding stages, cooling, resistance test, CCD inspection, tray output and NG rejection. For the AC route, the main reduction is one resistor and the related resistor feeding/transfer mechanism.

Item	Confirmed specification
Transport	Front and rear eight-station ring-type magnetic levitation loops
Inspection	Two CCD systems, with front and rear display/touchscreen interfaces
Welding	Two three-axis laser welding modules; validation note lists 3 seconds per single weld point and six weld points
Testing	Resistance test with CCD appearance inspection and standard-sample station
Tray handling	Nonstop tray loading/unloading with waiting tray and finished tray warehouses
Control package	One control system
Capacity	Average 300 to 350 products per hour
Changeover constraint	Dedicated machine; product changes require replacement of all fixtures and grippers

Proposed operating result

The resulting line gives the production team a detailed automation route for AC/DC socket bushing assembly, from component feeding and forming through laser welding, resistance testing, CCD appearance inspection and tray unloading.

Process value

The value is integration across many small, tolerance-sensitive steps: taped thermistor forming, plastic-housing feeding, resistor handling, fixture-based magnetic-loop transfer, laser welding, test verification and NG removal are all tied into one controlled route. The available project data does not include equipment price, labor saving or payback period, so we do not assign an ROI figure.