Spot Welding Press-Force Pulsation for Stable Multi-Sheet Joints
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Solution Overview
Problem
Existing spot welding methods maintain constant pressing force during each step, which does not allow for variations in force, leading to inefficiencies and potential issues like spatter and dust formation.
Innovation Solution
Implementing a pulsating pressing force variation step before main energization in spot welding, allowing for increased and decreased pressure within one step to improve contact stability and joint strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant pressing force is applied during spot welding steps, then the welding process is simple to control, but the contact state between sheet materials is insufficient leading to spatter and dust formation
Solution Approach 1:
The patent applies periodic action by implementing a pressing variation step that pulsates the pressing force before main energization. This periodic variation in pressing force improves the contact state between sheet materials, preventing spatter and dust formation during the welding process while maintaining simple control mechanisms.
2Manufacturing precision
If pressing force is varied between different steps, then the welding quality improves, but the control complexity increases
Solution Approach 1:
The patent segments the welding process into distinct steps: a pressing variation step with pulsating force before energization, and a main energization step. This segmentation allows pressing force variation to improve welding quality while keeping the control logic structured and manageable through clear step differentiation.
3Object-generated harmful factors
If pulsating pressing force is applied prior to main energization, then spatter and dust are suppressed, but the process time increases
Solution Approach 1:
The patent applies preliminary action by implementing the pressing variation step with pulsating force before the main energization step. This preliminary pressing action prepares the sheet materials by improving their contact state, which subsequently suppresses spatter and dust during energization. The pulsating nature of the pressing force allows this preparation to be achieved efficiently without excessive time consumption.
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 stabilizes the welding process, reduces spatter and dust, and achieves desired joint strength characteristics by improving the contact state between sheet materials during energization.
Implementation Method 1
a pressing variation step of, prior to the main energization step, causing a pulsation of pressing force applied to the set of sheets from the electrodes
Implementation Method 2
Spot welding is one type of resistance welding using Joule heating, which is performed by energizing stacked sheet materials with a large current for a short time
Implementation Method 3
the energization forms a molten pool in the vicinity of a contact interface (portions to be joined) between the stacked sheet materials
Implementation Method 4
the molten pool is cooled and solidified into a welded portion (nugget)
Data Source
AI summary
A spot welding method including: a main energization step of energizing a pair of opposing electrodes in pressure contact with both outer surfaces of a set of sheets where multiple sheet materials are stacked, thereby to cause melting between facing surfaces of the sheet materials; and a pressing variation step of, prior to the main energization step, causing a pulsation of pressing force applied to the set of sheets from the electrodes. A resin material such as an adhesive or a sealant may be interposed between the facing surfaces of at least a pair of the sheet materials. The period of the pulsation is 0.01 to 0.7 seconds. The amplitude of the pulsation is 10% to 90% with respect to a reference value of the pressing force. The set of sheets may include a first and a second steel sheet, and an aluminum alloy sheet that are stacked in order.