Conical Pin Assembly for Precise Flange Joint Tensioning
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Solution Overview
Problem
Existing methods for joining large structures, such as pipe flanges, face challenges in achieving precise and even tightening due to high frictional forces between screw heads and abutments, and require accurate centering of screws for even stressing and positioning.
Innovation Solution
A pin assembly with a pin head and nut featuring conical circumferential surfaces and radially expandable bearing sleeves, along with clamping bolts and plates, which center the pin within pin holes and apply radial clamping force through threaded holes and washers, ensuring precise alignment and tensioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large diameter screws are used to join large structures, then the joining strength is sufficient, but the frictional forces between screw head and abutment prevent precise and even tightening
Solution Approach 1:
The patent introduces a bearing sleeve as an intermediary component between the screw head/nut and the flange abutment surface. This bearing sleeve provides a low-friction interface that allows the screw to be tightened precisely without the high frictional forces that would otherwise exist between the large-diameter screw head and the flange surface. The bearing sleeve effectively mediates the interaction between the fastening elements and the structure being joined.
2Strength
If screws are used for joining, then the structures can be connected, but accurate centering of screws in pin holes is required to achieve even stressing
Solution Approach 1:
The bearing sleeve is designed with an externally tapered surface that cooperates with a corresponding internally tapered bore in the flange. As the screw is tightened, the bearing sleeve is automatically pushed into the tapered bore, causing it to expand radially and center itself within the pin hole. This self-centering mechanism eliminates the need for precise manual centering of the screw, while still achieving even stressing of the flange connection.
3Manufacturing precision
If bearing sleeves with tapered surfaces are used, then precise alignment and centering are achieved, but the device complexity increases
Solution Approach 1:
The bearing sleeve is segmented with axial slots that allow it to expand radially when pushed into the tapered bore. This segmentation enables the bearing sleeve to perform multiple functions: providing a low-friction interface, centering itself automatically, and accommodating the tapered engagement geometry. The segmented design simplifies the overall structure compared to attempting to achieve the same functionality with a solid, non-expandable component.
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 solution enables precise alignment and even stressing of flange connections by centering pins within pin holes and applying controlled tension, overcoming the limitations of high frictional forces and ensuring accurate positioning and radial clamping.
Implementation Method 1
internally conical, radially expandable bearing sleeves which are axially displaceable on the conical circumferential surfaces of the pin head and the nut, respectively
Implementation Method 2
the frictional forces between a screw head and the abutment of the screw head, possibly between a nut and the abutment of the nut, will prevent or complicate precise and even tightening
Data Source
Figure 1~2
Figure 3~4
AI summary
A pin assembly (1) with a pin head (12) and a nut (13) provided with conical circum- ferential surfaces (121, 131) falling towards first, outward -facing end faces (122, 132) on the pin head (12) and the nut (13); internally conical, radially expandable bearing sleeves (15) which are axially displaceable on the pin head (12) and the nut (13) and are provided with cylindrical, external sleeve surfaces (152), at least one of the pin head (12) and the nut (13) being provided with a set of first threaded holes (124, 134) and a set of second threaded holes (125, 135); a set of first clamping bolts (14) being arranged in the first threaded holes (124, 134); clamping plates (16) being ar- ranged to rest against an end face (154) on each of the bearing sleeves (15), as sets of second clamping bolts (17) extend through the clamping plates (16) and into the sets of second threaded holes (125, 135) of the pin head (12) and the nut (13), re- spectively. A flange joint provided by the pin assembly (1) is described as well.