Temperature-Stable SPR Coating for Crack-Free Hot Joining
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Solution Overview
Problem
Existing self-piercing rivet (SPR) systems are not satisfactory for joining new materials, as the coating can melt locally during the thermally assisted mechanical joining process, leading to crack formation due to liquid metal embrittlement or other effects.
Innovation Solution
A method involving a joining element with a temperature-stable coating, preheating at least one component to a temperature range of 90 °C to 1400 °C, and driving the coated joining element into the stacked components, thereby preventing coating melting and crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional coating is applied to the joining element, then corrosion protection and friction control are improved, but the coating melts locally during thermally assisted mechanical joining, leading to crack formation
Solution Approach 1:
The coating material composition is changed to have a melting point higher than the joining temperature. The patent specifies that the coating should have a melting point at least 100°C above the joining temperature to prevent melting during the thermally assisted mechanical joining process, thereby avoiding crack formation while maintaining corrosion protection.
Solution Approach 2:
The patent employs a multi-layer coating system where a base coating provides corrosion protection and a top coating provides friction control. Both layers are selected to have appropriate melting points above the joining temperature, creating a composite coating structure that maintains its integrity during high-temperature joining processes.
2Manufacturing precision
If preheating is applied to components before joining, then material flow and setting characteristics are improved, but the temperature causes conventional coatings to melt and embrittle the joining element
Solution Approach 1:
The coating's melting point parameter is changed to exceed the preheating temperature. The patent specifies that the coating should have a melting point at least 100°C above the joining temperature, ensuring that even with preheating to high temperatures, the coating remains stable and does not melt or embrittle.
Solution Approach 2:
The coating is designed with excessive thermal margin (melting point 100°C above joining temperature) to cushion against temperature variations and prevent harmful effects. This prior cushioning ensures that even if temperature control has some variation, the coating will not melt or cause embrittlement.
3Reliability
If a temperature-stable coating is used, then crack formation is prevented, but the coating may affect friction characteristics during the joining process
Solution Approach 1:
The patent uses a multi-layer coating system where the base coating provides thermal stability and corrosion protection, while a separate top coating layer provides optimized friction characteristics. Both layers are designed with melting points above the joining temperature, ensuring that friction control is achieved without compromising thermal stability or causing crack formation.
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
The use of a temperature-stable coating on the joining element allows for successful joining of components without cracking, even in thermally assisted mechanical joining processes, enhancing the reliability and durability of the joint.
Implementation Method 1
preheating at least one of at least two components in an area of a joining location to a temperature in the range from 90 °C to 1.400 °C, preferably by plasma-heating, laser-heating, electric arc heating and/or induction heating
Implementation Method 2
preheating at least one of at least two components in an area of a joining location to a temperature in the range from 90 °C to 1.400 °C, preferably by plasma-heating, laser-heating, electric arc heating and/or induction heating
Implementation Method 3
preheating at least one of at least two components in an area of a joining location to a temperature in the range from 90 °C to 1.400 °C, preferably by plasma-heating, laser-heating, electric arc heating and/or induction heating
Implementation Method 4
preheating at least one of at least two components in an area of a joining location to a temperature in the range from 90 °C to 1.400 °C, preferably by plasma-heating, laser-heating, electric arc heating and/or induction heating
Data Source
Figure 1~2a
Figure 3a~5b
AI summary
A method (10) for joining components (20, 22), particularly metal components, by means of a joining element (12) which is deformed during the joining process, comprising the following steps: coating (S2, S3) a joining element (12) with a temperature-stable coating (B1,B2) ; preheating (S6) at least one of at least two components (20, 22) in an area of a joining location to a temperature in the range from 90°C to 1.400 °C, preferably by plasma-heating, laser-heating, electric arc heating and/or induction heating, wherein the components (20, 22) are stacked on top of each other; and driving the coated joining element (12) into the stacked components (20, 22).