Case | How to Achieve Stable Automatic Loading & Unloading for Multiple Specifications of Materials

In the silicon material processing segment of the photovoltaic industry chain, silicon ingot depalletizing and loading acts as a critical link connecting warehousing and production. With continuous upgrades in production line capacity, traditional manual handling is plagued by high labor intensity and prominent efficiency bottlenecks. Furthermore, it cannot sustain long-term stable positioning accuracy when processing heavy-duty silicon ingots with diverse specifications.

Recently, Transfer Technology’s 3D vision intelligent loading and unloading solution has been successfully deployed on a domestic photovoltaic material production line. Tailored for multi-specification silicon ingot handling with dual-station stacking layouts, the solution adopts high-precision laser 3D vision as the core, enabling full-link collaboration of vision positioning, PLC scheduling and robot picking. It realizes fully automated, highly stable silicon ingot depalletizing and loading operations.

1. On-Site Working Conditions

This station is dedicated to automatic silicon ingot loading, which picks stacked silicon ingots from trays one by one and transfers them to the conveyor line. The on-site working conditions feature typical industry challenges:

• Diversified material specifications: Silicon ingots are available in two cross-sectional types, with lengths ranging from 100 mm to 850 mm. Multiple ingots of different lengths can be mixed in a single row and separated by foam spacers.

• Dual-station cyclic operation: A single workstation is equipped with two stacking positions. The vision system supports automatic switching between the two stations, enabling seamless cyclic operation — picking from one stack while replenishing materials at the other.

• High fault tolerance for incoming materials: Trays are delivered manually or by AGV. The vision system is required to independently adapt to random tray position deviations.

2. Solution

To address on-site operational demands, Transfer Technology adopts a cost-effective and high-performance configuration of single 3D camera + mobile module. One integrated vision system covers dual-station operations, balancing excellent performance and low investment costs.

Hardware Deployment & Field of View Adaptation

Equipped with the Epic Eye Laser L laser 3D camera, the system features an overhead installation above the stacking stations, paired with a mobile module to achieve flexible horizontal switching between dual stations. The camera supports a maximum working stack height of 3000 mm and fully covers the 1110 mm × 920 mm standard tray range. Even with placement deviations of trays, the 3D point cloud algorithm can accurately resolve and identify the precise position and pose of each silicon ingot.

Communication & Control Logic

The vision system communicates with the PLC in real time via TCP/IP Socket protocol. After receiving a shooting trigger signal from the PLC, the camera rapidly completes point cloud acquisition, automatically calculates the center coordinates, spatial pose and length parameters of silicon ingots, and feeds valid data back to the PLC. The PLC then dispatches the robot to execute accurate picking tasks.

Layered & Sequential Picking Adaptation

Cooperating with the on-site composite suction cup gripper, the vision system can intelligently distinguish silicon ingots from black trays. It supports independent positioning and one-by-one picking of multiple segmented ingots in a single row, ensuring consistent picking poses for each silicon ingot and effectively avoiding operational abnormalities such as material adhesion and picking offset.

3. Core Performance

After on-site commissioning and verification, the solution delivers stable and reliable performance with all indicators meeting production standards:

• Positioning Accuracy: Reaches ±3 mm, fully satisfying the high-precision alignment requirements for silicon ingot picking.

• Production Cycle: The full process of single-frame imaging, pose calculation and data communication takes only 2 seconds. Combined with fast station switching, it ensures high-efficiency and continuous on-site loading.

• Working Condition Adaptability: Achieves stable recognition for all silicon ingot specifications. It tolerates tray position deviations of up to ±50 mm, eliminating the need for rigid limiting tooling and simplifying on-site deployment.

The deployment of this 3D vision loading and unloading system completely replaces traditional manual depalletizing operations. It greatly reduces frontline labor intensity and operational safety risks, while stabilizing production cycle and minimizing positioning errors. It builds a solid visual perception foundation for the full-process intelligent upgrading of photovoltaic production lines.

The photovoltaic industry features extensive material handling scenarios for silicon ingots, silicon wafers and other heavy-duty, multi-specification workpieces. Transfer Technology’s replicable 3D vision solution is not only applicable to silicon ingot depalletizing, but also adaptable to various automatic loading, unloading and positioning scenarios in the photovoltaic sector. It empowers new energy manufacturing enterprises to achieve stable, efficient and flexible automated production upgrades.