Stack Turners and Plate Turners for Industry: Safely and Automatically Turning Large and Heavy Materials

Industrial sheet metal processing is under constant pressure to make processes more efficient, precise, and environmentally friendly. The pallet and blank turner from SYSTRAPLAN is an innovative solution whose unique selling point is the consistent avoidance of hydraulics in favor of a purely electromechanical drive concept. This approach not only increases energy efficiency and minimizes maintenance costs, but also enables unmatched precision in controlling the critical contact pressure.

Advantages of purely electric drive

The switch from hydraulic or pneumatic systems to electromechanical drives offers significant advantages in heavy-duty logistics:

• Maximum precision and controllability: Electric drives, especially in combination with rotary encoders and frequency converters, enable precise control of position, speed, and, above all, force (contact pressure). In contrast to hydraulics, where pressure is controlled via valves and pumps, the contact pressure can be adjusted directly and dynamically via the torque of the electric motor and the transmission ratio of the spindle.
• Low maintenance: The elimination of oil, hoses, seals, and filters eliminates the risk of leaks and drastically reduces maintenance and downtime.
• Energy efficiency: Electrical systems only consume energy when they are actively working. Hydraulic systems often require energy to maintain a constant static pressure.

Functional principle and process flow

The turning process is carried out in a sequential, safety-oriented process that ensures precise positioning and stable clamping of the stack.

1. Introduction of the empty pallet

The operator initiates the process via the control system and selects the appropriate pallet size.

• An empty pallet is manually positioned on the infeed roller conveyor using a forklift or crane.
• The pallet is weighed and aligned. This verifies the correct dimensions (matching the pallet of the blank stack) and ensures that the axes are paralle.
• The empty pallet is transported into the stack turner, positioned centrally by means of length measurement, and secured by the turner's clamps.
• The stack turner rotates empty by 180°. The original empty pallet is now in the upper holding position and serves as a “lid”.

2. Loading and positioning of the stack

The operator simultaneously places the pallet with the stack of blanks on the infeed roller conveyor.

• The loaded pallet is driven into the stack turner. Precise longitudinal positioning is achieved by a combination of sensors and a rotary encoder on the drive motor, which ensures high repeat accuracy.

3. The secure main turning process

This step is crucial for the stability of the blank stack during rotation.

• The two roller conveyors (top with empty pallet, bottom with stack of blanks) move toward each other until only the minimum distance remains. A calculated contact pressure is applied, the amount of which depends directly on the maximum weight of the stack.
• Once the required pressure has been reached, the spindles of the clamping mechanism are secured by a holding devices to prevent them from yielding during rotation.
• The secured unit rotates 180°. The stack of blanks now lies upside down between the original empty pallet (now at the bottom) and the original stacking pallet (now at the top).
• The clamp on the original stacking pallet (now at the top) holds the pallet in place and the roller conveyor, which is now at the bottom, is lowered. The “top pallet” (the original empty pallet) now holds the turned sheet metal stack.

4. Outbound and pallet management

The components are separated and prepared for the next cycle.

• The finished pallet with the stack of sheets (on top) is transported out on the “right” side of the infeed and is ready for the operator to pick up on the infeed roller conveyor.
• The pallet that originally carried the stack of circuit boards remains in the clamps of the upper roller conveyor.

Cycle flexibility and control

The system management enables a high cycle frequency thanks to the option of leaving the upper pallet in the turner:

• If the next pallet to be turned is of the same type, the pallet remaining on top can be used directly as a carrier pallet in the next cycle.
• If a change is necessary, the operator must use the control system to remove the remaining pallet in order to clear the turner for the new geometry.

This blank stack turner demonstrates a successful implementation of weight and position control for securing heavy stacks of blanks, which represents a significant improvement in quality and time savings in the logistics chain of sheet metal processing.

Flexibility of system configuration

SYSTRAPLAN systems can be customized to meet specific customer requirements, whether in terms of stack sizes and weights - turners for 14-ton stacks have already been implemented. This tailor-made solution ensures that production is efficient, high-quality, and tailored to the specific needs of the customer.