Offset Pivot Gripper Arms for Compact Metal Forming Transport
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Solution Overview
Problem
Conventional workpiece transport devices for forming machines require significant lateral space due to the wide pivoting motion of gripper arms, leading to increased space requirements and potential collisions during operation.
Innovation Solution
The design features gripper arms with offset pivot points, allowing them to pivot outward less widely, and incorporates a rotary drive mechanism that is more compact and easier to seal than linear drives, along with a prestressing device to maintain the gripping position and prevent flapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gripper arms are designed to pivot outward widely to achieve full opening motion, then the gripping range and opening capability are improved, but the lateral space requirement increases significantly
Solution Approach 1:
The patent applies asymmetry by positioning the fixed pivot points of the links at different lateral locations relative to their respective gripper arms. Specifically, the fixed pivot point of one link is arranged closer to the other gripper arm than the fixed pivot point of the other link is to its own gripper arm. This asymmetric arrangement creates an offset pivot mechanism that reduces the lateral swing width of the gripper arms while preserving the full opening and closing motion capability, thereby resolving the contradiction between gripping range and lateral space requirement
Solution Approach 2:
The patent transitions from a symmetric lateral pivoting mechanism to an asymmetric offset pivot mechanism that utilizes longitudinal positioning of pivot points to achieve the same functional range of motion with reduced lateral displacement. By changing the dimensional arrangement of the pivot points along the longitudinal axis rather than maintaining symmetric lateral positioning, the system achieves compact lateral profile while maintaining full gripping adaptability
2Ease of operation
If a linear drive mechanism is used to actuate the guide head, then the gripping motion can be directly controlled, but the sealing complexity and space requirement increase
Solution Approach 1:
The patent replaces the linear drive mechanism with a rotary drive mechanism that acts on the links to rotate them about their fixed pivot points. This substitution transforms the actuation method from linear motion of the guide head to rotational motion of the links, which simplifies the sealing requirements since rotary joints have simpler sealing solutions compared to linear guides. The rotary drive still achieves precise control of the gripping motion through the mechanical advantage of the linkage system
Solution Approach 2:
The patent introduces the links as intermediary elements between the drive mechanism and the gripper arms. Instead of directly driving the guide head linearly, the rotary drive rotates the links, which then translate this rotational motion into the desired gripping motion through their articulation with the gripper arms. This intermediary mechanism allows the use of a simpler rotary drive with easier sealing while maintaining the required gripping control
3Use of energy by moving object
If the gripper arms are held in the gripping position without active drive, then energy consumption is reduced, but the gripping force may be insufficient and undefined flapping may occur
Solution Approach 1:
The patent employs a prestressing device that exerts a force on the guide head in the direction of the gripping ends of the gripper arms. This prestressing force acts as a counterbalancing mechanism that maintains the gripper arms in the gripping position without requiring continuous active drive. The prestressing device compensates for gravitational effects and ensures stable gripping force, preventing undefined flapping of the gripper arms while minimizing energy consumption by allowing passive holding of the gripping position
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
A work transport device for a metal-forming machine comprises a pair of grips (1) which have two non-crossing gripper arms (11, 12) which are pivotable relative to one another and which each have a gripping end (111, 121) for gripping a workpiece (9). Each of the two gripper arms (11, 12) is coupled to a common guide head at the end (114) opposite the gripping end (111, 121) and to a separate link (13, 14) in a central region between the two ends. The two links (13, 14) are each rotatable about a fixed pivot (140). According to the invention, the fixed pivot (140) of the link (13, 14) of the one gripper arm (11, 12) is arranged closer to the other gripper arm (11, 12) than the fixed pivot (140) of the link (13, 14) of this other gripper arm (11, 12). As a result, the two gripper arms (11, 12) are swung outwards to a smaller extent when being swung apart.