Extended Nip Roll Beveled Surface Pressure Profile
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Solution Overview
Problem
Existing extended nip presses in paper making machines face challenges in achieving a suitable pressure profile and reliable lubrication, leading to issues such as re-wetting of the paper web and potential damage from unintended pressure peaks.
Innovation Solution
An extended nip roll with a flexible jacket and an elastically deformable press body, featuring internal pressure chambers and a beveled working surface, which allows for a progressive pressure increase to a peak at the nip's end, and incorporates a harder sole for the working and exit surfaces to prevent secondary pressure peaks, along with optional lubrication and wear protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid shoe with concave surface is used in the extended nip roll, then structural strength and stability are improved, but the ability to achieve a suitable pressure profile and adapt to the counter roll is worsened
Solution Approach 1:
The patent replaces the traditional rigid steel shoe with a flexible press body made of elastomeric material that can be pressurized. This flexible press body conformably adapts to the counter roll surface while maintaining sufficient structural strength through internal pressurization, thereby resolving the contradiction between structural strength and adaptability.
Solution Approach 2:
The patent introduces internal pressure chambers within the press body that can be connected to a pressure medium source. By controlling the pressure of the medium, the press body can be pressurized to expand and conform to the counter roll, achieving a suitable pressure profile without requiring a rigid structure, thus resolving the contradiction between strength and adaptability.
2Stress or pressure
If pressure chambers are set under different pressures to obtain a stepped pressure curve, then pressure profile control is improved, but lubrication reliability and prevention of unintended pressure peaks are worsened
Solution Approach 1:
The patent changes the geometric parameters of the pressure chambers, specifically making the downstream pressure chamber longer than the upstream chamber. This geometric parameter change, combined with gradual pressurization, creates a smooth progressive pressure increase rather than a stepped curve, preventing unintended pressure peaks and ensuring reliable lubrication throughout the press nip.
3Adaptability or versatility
If the press body is made entirely of soft elastomeric material, then adaptability to counter roll is improved, but structural strength and prevention of web damage are worsened
Solution Approach 1:
The patent uses a composite structure where the press body is made of elastomeric material for adaptability, but the working surface is reinforced with a harder material layer. This composite construction provides both the conformability needed for adaptation and the structural strength required to prevent web damage, resolving the contradiction between adaptability and strength.
4Stress or pressure
If a beveled working surface with downstream exit side surface is used, then pressure profile progression is improved, but manufacturing complexity is worsened
Solution Approach 1:
The patent forms the beveled working surface and downstream exit side surface by molding the flexible press body in a desired shape. This approach allows complex geometric features to be created through a single molding process rather than requiring multiple machining steps, thereby reducing manufacturing complexity while achieving the desired pressure profile progression.
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
The solution enables a reliable pressure profile that reduces re-wetting and web damage, ensuring effective dewatering and maintaining lubrication, while allowing for accurate adaptation to the counter roll for consistent pressure distribution.
Implementation Method 1
The press body is elastically deformable and it has a top side that faces the interior surface of the flexible jacket. The press body further has at least a first and a second internal pressure chamber which internal pressure chambers can be pressurized such that the press body expands.
Implementation Method 2
in that the working surface and the exit side surface are made of a material that has a higher shore A hardness than the material in the rest of the press body
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to an extended nip roll (5) capable of forming a press nip (N) with a counter roll (7) which press nip (N) has an extension in a machine direction when the extended nip roll (5) cooperates with the counter roll (7). The extended nip roll (5) comprises a flexible jacket; an elastic press body (13) arranged inside the flexible jacket. The top side (14) of the press body (13) is beveled in such a way that, in the machine direction, a working surface (15) of the top side has a downstream end (16) which, in the machine direction, is followed by an exit side surface (17) that diverges from the interior surface (11) of the flexible jacket (10).The press body (13) further has at least a first and a second internal pressure chamber (18, 19). The pressure chambers (18, 19) can be pressurized such that the press body (13) expands. The first internal pressure (18) chamber has an extension in the machine direction that does not extend beyond the working surface (15) and the second internal pressure chamber (19) is located downstream of the first internal pressure chamber (18) and has an extension in the machine direction beyond the downstream end (16) of the working surface (15). The working surface (15) and the exit side surface (17) are made of a material that has a higher shore A hardness than the material in the rest of the press body (13). The invention also relates to an extended nip press and a paper machine in which the extended nip roll is used. The invention further relates to a method of operating the extended nip press.