Gripper Control Using Downholders for Clean Blank Release
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Solution Overview
Problem
Existing gripper systems face challenges in removing blanks from a fiber web without getting stuck, due to frictional fits or form fits at the edges, which can impair the position of the material web and the lifted blank.
Innovation Solution
The gripper system uses a grid-like distribution of gripping elements, where those inside the blank's contour line are actuated to lift the blank, while adjacent elements outside the contour line act as downholders to hold back the material web, ensuring trouble-free removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If only gripping elements within the blank contour are actuated to lift the blank, then the blank can be selectively removed, but the blank may get stuck on the edge of the remaining material web due to frictional fits or form fits
Solution Approach 1:
The gripping elements are divided into two functional groups: those within the blank contour for lifting and those outside the contour as downholders. This segmentation allows independent control of lifting and holding functions, enabling reliable blank removal without sticking to the remaining web.
Solution Approach 2:
The downholder gripping elements act as an intermediary mechanism between the lifting elements and the material web. By holding down the web at locations outside the blank contour, they prevent the web from interfering with blank removal, thus mediating the interaction between the gripper and the material web.
2Reliability
If gripping elements are placed against the material web as downholders outside the blank contour, then the material web is held back preventing sticks, but the gripper structure becomes more complex
Solution Approach 1:
The gripping elements serve dual functions: they can act as lifting elements when positioned within the blank contour and as downholders when positioned outside the contour. This multi-functionality reduces the need for separate dedicated downholder mechanisms, thereby limiting the increase in device complexity.
Solution Approach 2:
The gripping elements are designed to be dynamically controllable, allowing each element to be independently actuated or deactivated based on its position relative to the blank contour. This dynamic control enables the same gripping element to serve different functions (lifting or holding) as needed, avoiding the need for separate static structures.
3Device complexity
If all suction heads are lowered together onto the cutting table, then the gripper structure is simpler, but the blanks may get stuck on the edge of the fiber layer during removal
Solution Approach 1:
Different gripping elements are assigned different functions based on their local position relative to the blank contour. Elements outside the contour are specifically designated as downholders to address the local problem of edge friction, while elements inside the contour serve as lifting elements. This localized functional assignment eliminates edge sticking without requiring complex overall restructuring.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the successful release and lifting of blanks from the material web without interference, maintaining the position of the material web and ensuring accurate lifting of the blank.
Implementation Method 1
a common suction box for receiving a vacuum pressure
Data Source
AI summary
A gripper, which removes blanks from a web of material lying flat, includes gripping elements which can each be actuated separately. The gripping elements are mounted independently of one another in a frame so as to be displaceable perpendicularly to a reference plane parallel to the web of material. The gripping elements are set against the web of material and actuated in a takeover position of the gripper aligned with respect to the blank by means of a control device. In addition to the gripping elements located inside the contour line, there are also other gripping elements adjacent to the blank and located outside the contour line that are set against the material web as downholders. Gripping elements within the contour line of the blank are actuated and retracted from the material web, taking along the blank, before the gripper is lifted off the material web from the takeover position.