Torque-Limiting Nut Holder With Claws for Hammered Anchors
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Solution Overview
Problem
Existing torque-limiting devices fail to reliably secure nuts during hammering operations with expansion anchors, leading to potential loss of the holding element and inability to maintain torque limiting and setpoint torque checking due to inertial forces.
Innovation Solution
Incorporating holding claws on the receiving part of the device that secure the nut in a form-fitting manner, preventing it from being dislodged during hammer blows, and utilizing a monolithic design with metallic materials for enhanced reliability and ease of manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nut is secured only by friction-based clamping elements during hammering, then the device structure remains simple, but the nut may be dislodged by inertial forces during hammer blows
Solution Approach 1:
The holding element is segmented into functional zones: the receiving part with the receptacle, the holding claws extending radially inward to secure the nut, and the top part with the entrainment profile. This segmentation allows each zone to perform its specific function optimally while maintaining overall structural integrity.
Solution Approach 2:
Instead of using clamping elements that act laterally against the nut's side walls, the holding claws act axially on the front end face of the nut. This inverted approach of acting from the front rather than the side provides more reliable securing against hammer blows while simplifying the manufacturing process.
2Ease of manufacture
If clamping projections act against the side walls of the nut, then the nut may be secured during normal operation, but manufacturing complexity increases due to difficult-to-produce undercuts
Solution Approach 1:
The holding claws act on the front end face of the nut rather than the side walls, inverting the conventional approach. This allows the nut to be pressed axially into the receptacle during manufacturing without requiring complex lateral undercut features, significantly simplifying the casting or forming process while maintaining reliable securing.
Solution Approach 2:
The holding claws are pre-formed as integral features of the receiving part before the nut is installed. The nut is then pressed axially into the receptacle where the holding claws engage with its front end face, establishing the securing action in advance during the assembly process rather than requiring complex post-assembly adjustments.
3Strength
If the holding element has significant mass, then the device structure remains robust, but inertial forces during hammer blows may drive the nut forward out of the holding element
Solution Approach 1:
The holding claws are positioned to act as obstacles against which the nut strikes on the front side during hammering. This preliminary anti-action prevents the nut from being driven forward by inertial forces, countering the harmful effect before it can compromise the torque limiting function.
Solution Approach 2:
The inertial forces generated by the mass of the holding element during hammer blows, which would normally be harmful by driving the nut forward, are converted into a beneficial securing mechanism. The holding claws utilize these forces by providing an axial stop that the nut engages with, transforming the harmful inertial motion into a locking action that enhances reliability.
Data Source
AI summary
A device for torque limiting, which includes a nut and a holding element including a top part having an entrainment profile in a rear area for the rotatably fixed coupling of the top part with a setting tool. A receiving part has a receptacle in a front area of the holding element, in which the nut is rotatably fixedly accommodated. A device for torque transmission from the top part to the receiving part connects the top part and the receiving part and breaks at a limiting torque, interrupting the connection between the top part and the receiving part. The holding element includes at least one holding claw situated on the receiving part and securing the nut in the receptacle on the front side of the nut. A fastening arrangement made up of an expansion anchor and a device of this type for torque limiting as well as a method for manufacturing a device of this type.