Yankee Cylinder Section Jointing With External Narrow-Gap Welding
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Solution Overview
Problem
The manufacturing of Yankee cylinders is challenging due to stringent requirements for inner pressures, leak-tightness, and large diameter, leading to time-consuming and costly processes with high risks of weld imperfections and hazardous working conditions.
Innovation Solution
The process involves using workpieces with specific reinforcement flanges and welding bevels for narrow gap welding, reducing the need for internal welding and allowing for pre-fabricated grooves, which minimizes material consumption, residual stress, and deformation, and enables machining outside the cylinder to achieve precise dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional welding and machining procedures are used to manufacture Yankee cylinder sections, then the cylinder can be assembled, but the process is time-consuming (250+ hours), costly, and produces high risks of weld imperfections
Solution Approach 1:
The invention applies preliminary action by pre-fabricating grooves on the inner circumferential wall of the cylinder shell before welding operations. These pre-fabricated grooves eliminate the need for subsequent internal welding and machining operations, directly reducing manufacturing time and eliminating sources of weld imperfections. The grooves are created in advance when the workpiece is still accessible and can be easily formed, avoiding the need for operators to work inside the confined hot space later.
Solution Approach 2:
The invention extracts the welding operation from the internal confined space by performing all welding from the external side of the cylinder shell. The welding bevel is configured on the outer surface, allowing welders to access and perform welding operations externally without entering the hot, confined internal space. This extraction eliminates safety hazards and improves weld quality while reducing manufacturing time.
2Ease of manufacture
If welding is performed inside the hot, confined cylinder space, then joints can be formed, but operator safety is compromised and welding quality deteriorates due to difficult working conditions
Solution Approach 1:
The invention applies inversion by reversing the conventional welding approach: instead of welding from the internal side of the cylinder shell, all welding operations are performed from the external side. The welding bevel is configured on the outer surface, and reinforcement flanges extend outward to provide welding surfaces. This inversion completely eliminates the need for operators to work inside the hot, confined space, resolving both accessibility and safety issues.
Solution Approach 2:
The invention introduces reinforcement flanges as intermediary structures that extend outward from the cylinder shell. These flanges provide external welding surfaces and act as mediators that transfer the joint formation process from the internal confined space to the external accessible environment. The flanges enable welding to be performed externally while still achieving the required joint strength and integrity.
3Manufacturing precision
If multiple machining and welding steps are performed sequentially (TIG, gap removal, GSMA, surface machining), then precise dimensions are achieved, but the process complexity and cost increase significantly
Solution Approach 1:
The invention applies preliminary action by pre-fabricating grooves to the final required dimensions before welding operations. These grooves are created when the workpiece is still accessible and can be easily formed to precise specifications. By establishing the final groove geometry in advance, the invention eliminates subsequent machining steps while maintaining dimensional accuracy, thereby reducing process complexity.
Solution Approach 2:
The invention merges multiple separate operations into a single integrated process. By configuring the welding bevel and reinforcement flanges to work together as a unified system, the invention combines groove formation, welding, and surface preparation into one streamlined process. The reinforcement flanges and welding bevel are designed as integrated features that eliminate the need for separate gap removal and surface machining operations.
Data Source
AI summary
The present invention relates to a process for manufacturing a Yankee cylinder. The process comprises welding the first reinforcement flanges of two workpieces of Yankee cylinder section from inside of the cylinder case, preheating and welding the two workpieces of Yankee cylinder section from outside of the cylinder case, and then removing the first, second reinforcement flanges, radial inner end area of the weld and their surrounding material in the workpieces of the Yankee cylinder section, so that the joint of the two workpieces of Yankee cylinder section is machined to meet the final dimension requirements for the Yankee cylinder inner grooves. The present invention is also related to a workpiece of Yankee cylinder section used in the said process.