Stack Lifting Device Dual-Edge Sensor Control
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Solution Overview
Problem
Existing stack lifting devices in sheet processing machines face challenges in reliably and quickly feeding sheets of different thicknesses to further processing machines, as they often struggle to maintain stability and consistency in sheet separation and transport.
Innovation Solution
A dual-control loop system is implemented, where sensors monitor the top edges of the stack at the front and rear, with the front edge controlling the height of the suction head and the rear edge controlling the speed of the pile lift drive, using a feeler foot and digital sensors to maintain constant position and ensure accurate sheet separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensor controls the stack lifting device via the front upper edge of the stack, then the device structure remains simple, but the sheet separation and transport stability deteriorates due to indirect control
Solution Approach 1:
The control system is segmented into two independent control loops: one controlling the suction head position via front edge sensor, and another controlling the stack lifting speed via rear edge sensor. This segmentation allows direct control of sheet separation (front) and stack position (rear), improving reliability without excessive complexity
Solution Approach 2:
Two sensors provide direct feedback signals to the controller: front edge sensor feedback controls suction head positioning, and rear edge sensor feedback controls stack lifting speed. This dual feedback mechanism ensures stable sheet separation and transport by continuously adjusting based on actual stack position
2Device complexity
If the stack lifting speed is controlled based on front edge position, then the control mechanism is simplified, but the rear top edge position fluctuates affecting sheet separation
Solution Approach 1:
Instead of controlling stack lifting speed based on front edge position (conventional approach), the patent inverts the control logic by using the rear edge position as the primary control parameter. The rear edge sensor directly controls the lifting speed, ensuring the rear top edge remains at the target position, which directly improves sheet separation stability
3Productivity
If sheets of different thicknesses are fed quickly, then productivity increases, but the stability and consistency of sheet separation deteriorates
Solution Approach 1:
The stack lifting speed is dynamically adjusted based on sheet thickness and rear edge position feedback. The controller modifies the lifting speed in real-time according to the detected thickness variations, allowing fast feeding of different thickness sheets while maintaining consistent sheet separation through continuous adaptive control
Data Source
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AI summary
The method involves calculating speed of a stack lifting drive (6) in a controller (61), and lifting a sheet stack at the calculated speed. An actual position of a backmost upper edge of the stack is determined by a sensor (26) and a touching base (25) at a preset machine angle (16). The calculated speed is adjusted when the actual position differs from a target position. An anterior upper edge of the stack is measured by another sensor (32) at the machine angle. Height of a suction head (20) is adjusted when an actual position of the anterior upper edge differs from a desired position. An independent claim is also included for a device for controlling a stack lifting device of a sheet processing machine.