Rotating Drum Inlet Sealing for Larger Waste Paper Bales

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Solution Overview

Problem

Existing waste paper treatment processes using rotating drums face issues with leakage and wear due to large inlet openings, necessitating a safe and simple sealing solution.

Innovation Solution

A non-rotating inlet hopper is positioned centrally and inclined to the drum's axis, with a labyrinth seal and conveyor bars to guide fibers away from the seal area, and additional conveying elements to manage large quantities, combined with lifting bars for mixing and partition walls to stabilize the process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the inlet opening is made larger to process larger waste paper bales, then productivity is improved, but leakage and wear on sealing elements worsen

Engineering Contradiction:
Improveinlet opening sizeVSAvoidsealing performance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The inlet is extracted from the rotating drum structure and made stationary, positioned in front of the drum rather than being part of the rotating assembly. This separation allows the inlet to remain fixed while the drum rotates, enabling larger inlet openings without compromising sealing at the interface between stationary and rotating components.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A stationary inlet hopper serves as an intermediary structure between the material feed and the rotating drum. The hopper is positioned in front of the drum and feeds material to the rotating inlet, acting as a mediator that allows large openings while maintaining reliable sealing at the stationary-rotating interface.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the inlet is made stationary to improve sealing, then reliability is improved, but the ability to transport fiber into the drum may be reduced

Engineering Contradiction:
Improvesealing performanceVSAvoidfiber transport efficiency
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

While the inlet structure itself is stationary, the rotating drum with its inclined axis and internal conveying elements provides dynamic fiber transport. The rotation of the drum creates lifting and sliding motions that efficiently move fibers from the stationary inlet into the processing zone, combining structural stability with operational dynamics.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The drum is inclined at a maximum of 10° to the horizontal, introducing a dimensional component that aids fiber transport. This inclination, combined with the stationary inlet positioning, creates a geometry that naturally guides fibers into the drum while maintaining reliable sealing at the interface.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 configuration allows for larger inlet openings, reducing the effort required to process waste paper bales and minimizing leakage and wear, while maintaining efficient fiber transport and mixing.

Implementation Method 1

the conveyor bars are tilted relative to the rotation axis. This means that the end of the conveyor bar pointing in the conveying direction trails in the direction of rotation

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 2

the water-mixed waste paper is shredded in the dissolving zone of the usually horizontal cylinder/drum by lifting, sliding, and falling

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 3

the water-mixed waste paper is shredded in the dissolving zone of the usually horizontal cylinder/drum by lifting, sliding, and falling

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 4

the transition between the stationary drum and the rotating drum must be sealed using a labyrinth seal

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3347521B1Rotating drum
Publication Date: 2025.10.08 VOITH PATENT GMBH
  • EP3347521B1 patent drawingFigure 1~2
  • EP3347521B1 patent drawingFigure 3~4

AI summary

The invention relates to a rotating drum for treating a fibrous material (1), wherein the rotational axis (2) of the drum is inclined by maximally 10° relative to the horizontal. The drum comprises a dissolving zone (4) which adjoins a base (3) of the drum, into which the fibrous material (1) is supplied via an inlet (5) at said base (3), and in which the fibrous material is mixed with water in order to form a fibrous material suspension. Large drum diameters with as little leakage as possible at the inlet (5) can be achieved in that conveyor elements (6) are arranged on the inner face of the drum in the region of the inlet (5), said conveyor elements conveying the fibrous material (1) and the water axially away from the adjoining base (3) of the drum.