Sliding Electric Contact Device for Roller Welding Heads
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Solution Overview
Problem
Roller welding machines face challenges with high manufacturing costs and wear issues due to complex sliding contact systems, requiring frequent replacements and complex fabrication processes, and alternative solutions using mercury are environmentally hazardous.
Innovation Solution
A sliding electric contact device for roller welding machines featuring a bimetallic plate and composite current-carrying block with a sliding disk and internal support, allowing for easy replacement of wearable parts without dismounting the shaft, fabricated without complex laser welding operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sliding contacts are used with radial pressing against the shaft, then electric current transmission is achieved, but the sliding contacts are subjected to wear and tear requiring frequent replacement and complex disassembly
Solution Approach 1:
The sliding contact system is divided into modular components: the sliding block with replaceable sliding surface, the shaft with integrated mounting features, and the pressing mechanism. This segmentation allows the sliding surface to be replaced independently without replacing the entire shaft or disassembling the whole assembly, directly addressing the repair complexity issue while maintaining reliability through replaceable wear components
Solution Approach 2:
Instead of pressing the sliding contact radially against the shaft circumference (traditional approach), the invention inverts the arrangement by having the sliding block press axially against the shaft end surface. This inversion changes the wear pattern and allows for easier replacement while maintaining effective electrical contact, resolving both reliability and repairability concerns
2Reliability
If complex laser welding operations are used to fabricate sliding contacts, then strong electric connections are achieved, but manufacturing costs increase
Solution Approach 1:
The sliding block and shaft are designed with homogeneous material composition (both copper-based) to eliminate the need for complex heterogenous joining processes like laser welding. This homogeneity allows for simpler fabrication methods such as casting or forging while maintaining strong electrical connections, directly reducing manufacturing costs without compromising connection reliability
Solution Approach 2:
The invention merges the sliding contact function with the structural shaft component by integrating the mounting features directly into the shaft design. This consolidation eliminates separate welding operations and reduces the number of manufacturing steps, lowering costs while ensuring reliable electrical connection through the integrated design
3Reliability
If mercury-based solutions are used for sliding contacts, then wear issues are avoided, but environmental hazards are introduced
Solution Approach 1:
The sliding surface is designed as a replaceable component with limited service life, intended to be periodically replaced rather than maintained indefinitely. This disposable approach eliminates the need for toxic mercury-based self-lubricating materials, removing environmental hazards while maintaining acceptable wear resistance through routine replacement of the affordable sliding block component
Solution Approach 2:
The sliding block incorporates self-lubricating properties through its material composition and surface characteristics, eliminating the need for external mercury-based lubricants. This self-service capability provides adequate wear resistance without introducing environmental hazards, allowing the system to function reliably with regular maintenance and component replacement
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 solution simplifies the replacement of wearable parts, reduces manufacturing costs, and avoids shaft wear, enabling efficient current transmission while eliminating the need for mercury-based solutions.
Implementation Method 1
a sliding disk composed of a second metal softer than the first metal, defining a second sliding electric contact face
Implementation Method 2
The contact resistance between the plates to be welded is generally much greater than the electric resistance of electrodes, than that of the plates themselves and than the contact resistances between electrodes and plates, thus the welding current will generate heat for Joule effect essentially in correspondence of the interface between the two plates
Implementation Method 3
The anode roller is cooled by contact with a ball bearing flange that has communicating grooves with the inner cavity of the shaft so as to define inner channels for circulating a coolant, so as to prevent the roller from overheating and melting the surface of the plate with which it comes into contact
Implementation Method 4
From a thermal point of view, the anode roller sinks heat from the joint so as to attain thermal equilibrium
Implementation Method 5
elastic means for pulling the anode roller towards the cathode electrode so as to press the two plates to be welded placed between the rollers or between a roller and a planar electrode
Implementation Method 6
a cave shaft is pivotally mounted by means of ball bearings
Implementation Method 7
The shaft may eventually be connected through gears to a motor for making it rotate, so as to have, with appropriate appliances, the constant control of the peripheral speed of the roller in all phases of the welding path
Data Source
AI summary
A sliding electric contact device for welding head for roller welding machines, having a bimetallic plate adapted to be fixed to a shaft of a welding head, having a protection base composed of a first metal, defining a first face destined to abut against an end surface of the shaft, and a sliding disk composed of a second metal softer than the first metal, defining a second sliding electric contact face; a composite current-carrying block, having a plait of electrical wires, an internal support made of metal, pushed against the sliding disk for realizing with the sliding disk a sliding electric contact, first means adapted to fix firmly a central portion of the plait to the inner support, second current-carrying means adapted to fix firmly a peripheral portion of the plait to current terminals of a stator of the welding head. A welding head having the sliding electric contact device and a related roller welding machine are also disclosed.