Flat-Head Staking Bolt Structure for Thin-Plate Fastening
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Solution Overview
Problem
Conventional staking bolts have low extraction load and slip torque when caulked onto thin metal plates, and they require a thick metal plate and object to be fastened for reliable nut tightening due to their design limitations.
Innovation Solution
A staking bolt design featuring a flat head with a whirl-stop protrusion having radially extending arms and a ring-shaped protrusion on the shank, where the minimum diameter of the whirl-stop protrusion's cross-sectional area is equal to or greater than the ring groove's area, and the outer diameter between the ring protrusion and external thread is less than the thread's root diameter, allowing for complete metal flow and nut fastening on thinner materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional staking bolt with a thick head and wave-form whirl-stop protrusion is used, then the bolt can be caulked and fixed to a thick metal plate, but the slip torque is as low as 10 Nm or less and the extraction load is insufficient
Solution Approach 1:
The invention changes the geometric parameters of the whirl-stop protrusion by making the head flat (reducing head thickness) and designing the whirl-stop protrusion with radially extending arms that have a specific cross-sectional area relationship with the ring groove. This parameter change allows the bolt to achieve sufficient extraction load while being suitable for thin metal plates.
Solution Approach 2:
The invention applies local quality by concentrating the caulked fixation function in the ring groove area rather than relying on the overall head thickness. The whirl-stop protrusion with radially extending arms is designed to locally plastic flow metal material into the ring groove, creating a strong mechanical interlock that provides high extraction load despite the flat head design.
2Strength
If a conventional staking bolt with a large head is used, then the bolt can be caulked and fixed to a thick metal plate, but it cannot be caulked onto thin metal plates and the nut cannot be tightened to the vicinity of the head
Solution Approach 1:
The invention changes the geometric parameters by making the head flat and designing the whirl-stop protrusion with a specific cross-sectional area (t × (D-d)/2) that is equal to or greater than the ring groove's cross-sectional area. This allows complete filling of the ring groove with metal material, achieving high slip torque even on thin metal plates.
Solution Approach 2:
The invention transitions from relying on head thickness (one dimension) to utilizing the cross-sectional area relationship between the whirl-stop protrusion and ring groove (two-dimensional area comparison). This dimensional shift enables effective caulking on thin plates by focusing the plastic flow in the radial direction rather than requiring substantial head thickness.
3Ease of operation
If the head and external thread are separated in conventional design, then the bolt structure is simple, but the nut cannot be tightened to the vicinity of the head when the total thickness is insufficient
Solution Approach 1:
The invention changes the structural parameters by making the head flat and positioning the external thread closer to the head, with the non-threaded portion having a smaller outer diameter than the root diameter of the external thread. This allows the nut to be tightened to the vicinity of the head even when the total thickness of the metal plate and object is small, while maintaining structural simplicity.
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 design achieves a higher slip torque and extraction load on thin metal plates, enabling reliable fastening even with thinner materials by ensuring complete metal flow into the ring groove and allowing deeper nut engagement.
Implementation Method 1
causes the metal material to plastically flow in the ring groove formed around the shank
Implementation Method 2
the slip torque (the torque at which the staking bolt begins to slip with respect to the metal plate) be large
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The staking bolt of the present invention includes a head 10 and a shank 11 having an external thread 12. At the upper end of the shank 11, a ring-shaped protrusion 20 and a ring groove 21 located closer to the head relative to the ring-shaped protrusion 20 are formed. The head 10 is flat, and on the bearing face 13, a whirl-stop protrusion 14 having a plurality of radially extending arms 15 protrudes with a thickness of t. The minimum diameter D between respective arms 15 is larger than the outer diameter d of the ring-shaped protrusion 20, and t × (D - d)/2 which is the longitudinal cross-sectional area A of the minimum diameter portion of the whirl-stop protrusion 14 is equal to or greater than the longitudinal cross-sectional area of the ring groove 21.