Expander Roll Specialists
We have over 70 years of expertise and experience
Osaka Dyeing and Weaving Machinery Co., Ltd.
OSAKA SENSHOKU MACHINERY CO.,LTD,
What is an expander roll?
The key to the quality of sheet products is "wrinkle removal" and "widening."
Basic knowledge about curved rolls that support stable operation of production lines.
"Functional rolls" are essential for all sheet processing processes
How can a curved roll simply rotate to remove those pesky wrinkles? The secret lies in the shape of the roll and the properties of the rubber.
An expander roll (or bow-shaped roll) is a curved rubber roll that is installed in production lines for papermaking, dyeing, film, printing, etc. to eliminate wrinkles and shrinkage in sheet products (webs).
Rather than being a standalone machine, by attaching it to equipment in each process, such as dryers, calendars, and coaters, it plays a role in dramatically improving product quality and yield.
Why does wrinkles disappear and the width increase just by rotating it?
Unique "curved structure" creates rational widening effect
The secret lies in the fact that the roll axis is curved in an arch shape.
1. Rotation and friction: The roll surface rotates around a curved, fixed axis and grips the sheet with the frictional force of the rubber.
2. Change in angle: From the center of the roll to both ends (edges), the angle toward the outside with respect to the sheet's traveling direction increases (θ1>θ2>θ3).
3. Outward pulling force: Due to this angle difference, the sheet is naturally pulled "from the center to the outside" along the rotating roll surface, smoothing out any wrinkles.
Illustration: The outward pulling force increases from the center of the roll toward both edges.
Installation theory to maximize performance
1. Basic principles: introduction, derivation and angle balance
To ensure the effectiveness of the expander roll, it is important to have the correct "paper feed direction." Always install the roll so that the sheet is fed from the "concave side" of the roll and fed out to the "convex side."
Figure 1: Basic installation orientation
The optimum "contact angle (wrap angle)" varies depending on the material and thickness of the sheet.
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Figure 2: Thin material/film settings (30° to 50°)
2. Paper, film, thin fabric
For delicate or thin materials, set the contact angle to a smaller value of around 30° to 50°.
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Figure 3: Thick/nonwoven fabric settings (60° to 80°)
3. Thick woven and nonwoven fabrics
For strong or thick materials, a contact angle of around 60° to 80° will be sufficient.
Important point: The contact angle (wrap angle) on the roll is the sum of the "introduction angle" and "exit angle" shown in the diagram. The ideal installation position is to adjust these two angles so that they are equal (so that the apex of the roll's curvature is at the center of the contact surface).
A pioneer of domestic expander rolls
Although the structure of an expander roll may appear simple, its lifespan and performance vary greatly depending on the internal structure and the rubber material selected. Osaka Dyeing and Weaving Machinery Co., Ltd. is a pioneering company in domestically produced expander rolls. The "OS Expander Roll," the culmination of technology cultivated over many years, is clearly different from ordinary products.
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Based on the basic principle, the internal structure has been optimized to achieve smoother and more reliable widening performance.
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We thoroughly listen to the customer's production conditions (chemicals, temperature, speed) and select the optimum material from a wide variety of special synthetic rubbers, including EPDM, silicone, and fluororubber.
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In addition to waterproofing, we offer a wide range of series to suit line characteristics, including ultra-low tension (L/M series) and high speed rotation.
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Overwhelmingly high quality through consistent domestic design and manufacturing. Fast and thorough support system, including rubber sleeve re-polishing and replacement after installation.