Soft Tube Surface Irregularities to Prevent Roller Mold Scraping
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Solution Overview
Problem
Existing sheet conveying rollers with irregularities on their outer peripheral surfaces face issues of irregularity scraping during manufacture due to mold undercuts, leading to surface defects and noise during operation, especially when made from rubber elastic bodies with low hardness.
Innovation Solution
The solution involves forming the soft tube with irregularities on its outer peripheral surface, where the root mean square slope (Sdq) is within the range of 0.03 to 0.50, allowing for reduced irregularity scraping and improved sheet conveyance performance, using injection or compression molding to minimize mold release issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the soft tube is made of rubber elastic body with low hardness (10 to 30° Shore A) to improve sheet conveyance performance, then the grip on sheets is enhanced, but the mold sticks stronger due to increased tackiness, causing irregularities to be scraped off during mold release
Solution Approach 1:
The patent changes the physical parameter of hardness from low (10-30° Shore A) to medium (40 to 85° Shore A), which reduces tackiness and prevents irregularity scraping during mold release, while still maintaining sufficient sheet conveyance performance
Solution Approach 2:
The patent uses thermoplastic elastomer as a composite material that combines the elasticity needed for sheet conveyance with higher hardness to reduce tackiness, avoiding the irregularity scraping problem associated with soft rubber materials
2Object-affected harmful factors
If knurled grooves are provided on the outer peripheral surface to prevent paper dust adhesion, then paper dust escapes to recesses, but the projected portions strongly contact the sheet and may form marks
Solution Approach 1:
The patent applies local quality by creating irregularities only in specific regions (first and second regions with different wrinkle patterns) rather than uniform knurled grooves, allowing paper dust to escape while the softer irregularity shapes prevent strong contact that causes marks
Solution Approach 2:
The patent uses wrinkle patterns with curved, rounded irregularities instead of sharp knurled grooves, which allows paper dust to escape to recesses while the curved surfaces distribute contact pressure and prevent concentrated marks on sheets
3Reliability
If the irregularities have steep slopes to improve sheet conveyance grip, then the grip force is enhanced, but the irregularities are more likely to be scraped off during mold release
Solution Approach 1:
The patent changes the slope parameter of irregularities from steep to gentle (Sdq of 0.03 to 0.50), which prevents irregularity scraping during mold release while maintaining sufficient sheet conveyance grip through the cumulative effect of distributed gentle irregularities
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 irregularity scraping and ensures effective sheet conveyance while minimizing surface defects and noise, maintaining consistent grip and reducing paper dust adhesion.
Implementation Method 1
a wrinkle pattern having a surface roughness Ra of 30 to 80 μm is formed on the outer peripheral surface of the sheet conveying portion
Implementation Method 2
a rubber-elastic soft material such as ethylene propylene rubber, urethane rubber, or thermoplastic elastomer is used so that it can grip and convey sheets such as paper
Implementation Method 3
a molding method using a mold such as press molding (compression molding) or injection molding is employed in order to form the above-mentioned wrinkle pattern
Implementation Method 4
a molding method using a mold such as press molding (compression molding) or injection molding is employed
Data Source
AI summary
Disclosed is a soft tube of a sheet conveying portion of a sheet conveying roller, including: a region with irregularities in an outer peripheral surface of the soft tube. The region has a root mean square slope Sdq within a range of 0.03 to 0.50.