Hardened Steel Nut Plate Spot Welding Without Weld Rivets
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Solution Overview
Problem
The use of hardened steel nut plates in car bodies requires additional weld rivets due to their inability to be welded after hardening, leading to increased assembly costs and complexities.
Innovation Solution
A nut plate made predominantly of hardened steel, specifically boron-alloyed steel with manganese, is welded directly to the car body using spot welding, eliminating the need for additional weld rivets and maintaining mechanical stability with reduced material thickness and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hardened steel is used for the nut plate to achieve mechanical stability with reduced material thickness and weight, then the nut plate cannot be welded after hardening, requiring additional weld rivets which increases assembly costs and complexity
Solution Approach 1:
The patent changes the chemical composition parameters of the steel by adding boron (0.0005-0.005 wt%) and manganese (1.0-1.5 wt%), which fundamentally alters the material's weldability after hardening. This parameter change allows the nut plate to maintain high strength while enabling direct welding without additional rivets, resolving the contradiction between mechanical stability and assembly complexity
Solution Approach 2:
The patent creates a composite steel material with specific boron and manganese content that combines the properties of high strength (from hardening) and good weldability. This composite material approach allows both hardening treatment for mechanical stability and subsequent welding for assembly, eliminating the need for additional weld rivets and reducing assembly complexity
2Ease of manufacture
If additional weld rivets are provided on the nut plate to enable welding after hardening, then the nut plate can be attached to the car body, but assembly costs increase due to the additional components and steps
Solution Approach 1:
The patent extracts and eliminates the additional weld rivet component from the assembly process. By modifying the base steel composition with boron and manganese, the nut plate itself becomes weldable after hardening, removing the need for separate weld rivet components and simplifying the manufacturing process
Solution Approach 2:
The patent makes the nut plate universally applicable for both structural support (through hardening) and welding attachment (through compositional modification). The single component performs multiple functions - providing mechanical strength and enabling direct welding - eliminating the need for specialized additional components and improving assembly efficiency
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 approach reduces assembly costs by eliminating the need for additional weld rivets while maintaining mechanical stability and weldability of the hardened steel nut plate, even after heat treatment, allowing direct integration with the car body.
Implementation Method 1
the hardened steel of the nut plate is welded directly to the car body by spot welding
Implementation Method 2
The nut plate is preferably hardened by heat treatment, preferably by bainitizing
Data Source
Figure 1
AI summary
A car body (1) includes a nut plate (2) predominantly made of hardened steel, wherein the hardened steel of the nut plate (2) is welded directly to the car body (1). A nut plate (2) as for use in direct welding to a car body (1) is also provided. A method for mounting a nut plate (2), which is predominantly made of hardened steel, to a car body (1), wherein the method involves welding the hardened steel of the nut plate (2) to the car body (1).