Yankee Cylinder End Cover Welding Sequence
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Solution Overview
Problem
Existing methods for manufacturing Yankee drying cylinders often result in non-uniform thickness due to heat deformations from continuous welding, leading to uneven drying results for tissue paper production.
Innovation Solution
A method involving a circular cylindrical steel shell with axial end covers welded at specific angular intervals (175°-185°) as separate points, followed by a continuous weld bead to minimize heat deformations and ensure uniform thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous welding is used to join end covers to the cylindrical shell, then the manufacturing process is simple and efficient, but heat deformations occur causing non-uniform thickness
Solution Approach 1:
The continuous welding process is segmented into multiple separate welding points distributed around the circumference of the end cover. Each welding point is separated by gaps, and the welding is performed in a specific sequence (e.g., 16-32 points at 175°-185° intervals) to distribute heat input evenly around the cylinder, preventing localized heat accumulation and deformation while maintaining manufacturing efficiency.
Solution Approach 2:
The welding process uses periodic action by alternating between welding and non-welding (gap) sections around the circumference. The welding points are arranged in a periodic pattern with specific angular spacing, creating a rhythmic heat input pattern that allows heat dissipation between welding zones, thereby preventing thermal distortion while maintaining productive manufacturing pace.
2Manufacturing precision
If multiple separate welding points are used to reduce heat deformation, then thickness uniformity is improved, but the welding process complexity increases
Solution Approach 1:
The welding process is divided into discrete, numberable welding points (16-32 points) arranged in a systematic pattern around the end cover circumference. This segmentation transforms a complex continuous welding operation into a series of simple, repeatable discrete welding actions at predetermined locations, making the process easier to control and execute while achieving uniform thickness.
Solution Approach 2:
The invention changes the welding parameters from continuous to discrete by specifying exact angular intervals (175°-185°) between welding points and defining the sequence of welding operations. These parameter changes standardize the process, reducing complexity through clear numerical specifications rather than requiring complex real-time control of continuous welding.
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 thickness variations in the shell, resulting in more even drying of fibrous webs and maintaining uniform properties in the final product.
Implementation Method 1
welding each end cover to an axial end of the shell at 16 - 32 separate welding points
Implementation Method 2
heat deformations from continuous welding, leading to non-uniform thickness
Data Source
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AI summary
The invention relates to a method of manufacturing a Yankee drying cylinder 1 for drying wet fibrous webs W by heat. The manufacturing method comprising the steps of: providing a shell 2 which is a circular cylindrical steel shell 2 with two axial ends 3, 4 and the shell 2 having a diameter in the range of 2 m - 8 m. Circumferential grooves 6 are formed on an internal surface 5 of the shell during some part of the manufacturing process. An end cover 7, 8 of steel is provided for each axial end 3, 4 of the shell 2 and each end cover 7, 8 has a circular circumference. The method comprises welding each end cover 7, 8 to an axial end of 3, 4 the shell 2. According to the invention, each end cover 7, 8 is welded to its respective axial end 3, 4 of the shell 2 at 16 - 32 separate welding points 12a, 12b, 12c, 12d.....12x that are made in a sequence, one after the other, and separated from each other along the circumference of the end cover 7, 8. For at least the first 8 welding points 12a, 12b, 12c, 12d.....12x, the welding points 12a, 12b, 12c, 12d.....12x are made in pairs of two in which the second welding point 12a, 12b, 12c, 12d.....12x in a pair is made directly after the first welding point 12a, 12b, 12c, 12d.....12x of that pair and the second welding point 12a, 12b, 12c, 12d.....12x in each pair is placed at an angular distance along the circumference of the end cover 7, 8 which lies in the range of 175°- 185° from the first welding point of that pair.