Expansion Anchor Sleeve Forming for Precise Circularity
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Solution Overview
Problem
Existing methods for manufacturing expansion anchors often result in sleeves with non-circular outer cross-sections due to overbending of sheet metal, leading to increased friction and reduced performance during installation, and inhomogeneous bending processes can further exacerbate shape deviations.
Innovation Solution
A method involving a tubular sleeve blank with a large outer diameter is used, which is reduced in diameter around a bolt through plastic deformation, ensuring a circular and uniform expansion sleeve with accurate alignment and increased stiffness, allowing for precise matching of inner and outer profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sheet metal sections are bent around the bolt to form expansion sleeves, then the manufacturing process is simple and cost-effective, but the outer cross-sections deviate from a precisely circular shape due to overbending and elasticity
Solution Approach 1:
Instead of bending the sheet metal to form a circular shape, the invention uses a pre-formed tubular sleeve blank that is already circular. The blank is placed over the bolt and then radially compressed to reduce its diameter, creating the expansion anchor assembly. This inverts the traditional approach by starting with the correct shape and deforming it radially rather than trying to form the shape through bending.
Solution Approach 2:
The invention changes the deformation parameter from angular bending to radial compression. By applying radial compressive forces to reduce the diameter of the tubular sleeve blank, the process achieves precise circularity that cannot be obtained through bending due to material elasticity and overbending effects.
2Manufacturing precision
If sheet metal sections are overbent beyond circular shape to compensate for elasticity, then a circular shape may be achieved after rebound, but excessive hammer blows are necessary during installation due to shape deviations
Solution Approach 1:
Rather than overbending and hoping for a circular shape after rebound, the invention starts with a perfectly circular tubular blank and uses radial compression to maintain that circularity throughout the process. This eliminates the need for overcompensation and ensures consistent circular geometry.
Solution Approach 2:
The tubular sleeve blank is prepared in advance with the correct circular shape and appropriate dimensions. By pre-forming the blank to the exact required geometry before assembly, the invention eliminates installation difficulties that would otherwise require excessive hammer blows to correct shape deviations.
3Reliability
If profiled sheet metal sections are used for inner profiling, then the expansion sleeve can engage with the bolt, but the variable stiffness causes inhomogeneous bending and greater shape deviations
Solution Approach 1:
Instead of bending profiled sheet metal sections, the invention uses a tubular blank with the inner profile already formed. The profiled blank is placed over the bolt and radially compressed, which maintains uniform deformation throughout the structure without the inhomogeneous bending that occurs with profiled sections.
Solution Approach 2:
The invention changes the deformation mode from bending to radial compression. This parameter change ensures uniform stress distribution throughout the tubular blank, preventing the localized and inhomogeneous deformation that occurs when bending profiled sheet metal sections with variable stiffness.
4Manufacturing precision
If the sleeve blank is reduced in diameter through plastic deformation around the bolt, then a precisely circular shape is achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The manufacturing process is divided into distinct steps: providing a pre-formed tubular blank with inner profile, placing it over the bolt, and then applying radial compression. This segmentation allows each step to be optimized independently, maintaining precision while managing complexity through process modularization.
Solution Approach 2:
The tubular sleeve blank is designed to be self-positioning on the bolt, with the inner profile naturally engaging with the bolt surface. This self-alignment feature reduces the complexity of positioning and alignment during manufacturing, allowing the radial compression to be applied directly without complex fixture systems.
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 method produces consistently round and reliable expansion sleeves with improved installation performance, reduced friction, and enhanced extraction forces, while being cost-effective and accessible in complex anchor shapes.
Implementation Method 1
the sleeve blank is reduced in diameter and formed into the finished expansion sleeve, in particular by plastic deformation of the sleeve blank
Data Source
AI summary
A method for manufacturing an expansion anchor is provided, in which a bolt is provided, which includes an expansion body for expanding an expansion sleeve surrounding the bolt, an annular sleeve blank having an opening is provided, the bolt is introduced into the opening of the annular sleeve blank, and the annular sleeve blank is reduced in diameter while the bolt is located in the opening of the annular sleeve blank. The invention also relates to expansion anchors, which may be obtained with the aid of the method according to the invention, in particular bolt-type anchors having closed annular expansion sleeves and, in particular, anchors having expansion sleeves with protruding noses, which are each situated on a closing fold of the expansion sleeve.