Shaftless Cutting Drum Supported by Contact Rollers
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Solution Overview
Problem
Existing cutting units require complex and time-consuming regrinding operations due to the need for exact concentricity and centring of cutting and anvil drums, which is challenging especially for the lower drum that is difficult to access.
Innovation Solution
A cutting unit design where the lower drum is shaftless and supported by contact rollers, allowing for vertical and transverse support, enabling easier regrinding without the need for exact concentricity with the arbour or bearing blocks, and allowing the lower drum to be pressed against the upper drum using a carrier connected to a pressing device for maintaining cutting pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lower drum is supported by bearing blocks on an arbour, then the drum is stable during operation, but the regrinding operation becomes complex and time-consuming due to the need for exact concentricity and centring
Solution Approach 1:
The arbour and bearing blocks are completely removed from the lower drum support system. The lower drum is made shaftless and is instead supported by roller elements that provide support without requiring precise concentricity, thus simplifying regrinding operations while maintaining operational stability
Solution Approach 2:
Roller elements are introduced as intermediary components between the lower drum and the frame. These rollers provide the necessary support and stability during operation but do not require the drum to be precisely centred, thereby resolving the contradiction between operational stability and ease of regrinding
2Force
If the lower drum is arranged below the upper drum with fixed bearing blocks, then the cutting pressure can be maintained, but the lower drum becomes difficult to access for regrinding
Solution Approach 1:
The fixed bearing blocks that obstruct access to the lower drum are removed. The lower drum is made shaftless and supported by rollers that allow easy access from below for regrinding operations while the pressing device maintains the necessary cutting pressure
Solution Approach 2:
The support system for the lower drum is made dynamic through the use of rollers that can accommodate movement and adjustment. This allows the drum to be easily accessed for regrinding while still maintaining stable operation and cutting pressure during use
3Manufacturing precision
If the drum is precisely centred on the arbour in bearing blocks, then the cutting depth and force are exact, but the regrinding operation requires very exact centring and concentricity
Solution Approach 1:
The arbour and bearing block centring system is completely removed. The lower drum is made shaftless and supported by rollers that inherently accommodate minor misalignments, eliminating the need for precise concentricity during both operation and regrinding
Solution Approach 2:
The support mechanism changes from rigid bearing blocks requiring precise centring to flexible roller elements that tolerate variations in position. This parameter change in the support system maintains cutting precision while dramatically simplifying regrinding operations
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 design simplifies the regrinding process by eliminating the need for precise centring and access issues, while maintaining the cutting unit's functionality and ensuring consistent cutting pressure and depth along the axial length.
Implementation Method 1
The lower drum is shaftless and is arranged with the outer cylindrical surface thereof resting on the outer cylindrical surface of the at least two contact rollers
Implementation Method 2
The carrier is connectable to a pressing device for moving and pressing the carrier and the lower drum carried thereby towards and against the upper drum for providing cutting pressure
Data Source
Figure 1
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AI summary
A cutting unit according to the invention comprises a stationary frame (1), a cutting drum (5) having a cutting knife (7) on an outer cylindrical surface thereof and a central axis, and an anvil drum (6) having an outer cylindrical surface and a central axis. The cutting drum (5) and the anvil drum (6) are arranged one over the other with parallel centre axes for cutting web material fed between them. The upper of the cutting drum (5) and the anvil drum (6) is centred on an arbour, which is rotatable supported in the stationary frame and connectable to a driving device for rotating the arbour and the upper drum around the centre axis thereof. The lower of the cutting drum and the anvil drum is arranged rotatable around the centre axis thereof, and is arranged movable towards and away from the upper drum. The cutting unit further comprises a carrier (16), which is arranged movable towards and away from the upper drum. The carrier (16) comprises at least two contact rollers (19), which have an outer cylindrical surface and which are arranged rotatable round a respective axis in the carrier, which axes are parallel to the centre axis of the cutting drum (5) and the anvil drum (6). The lower drum is shaftless and is arranged with the outer cylindrical surface thereof resting on the outer cylindrical surface of the at least two contact rollers (19), wherein at least one contact roller (19) is situated on either side of a central vertical plane of the lower drum for providing vertical and transversal support of the lower drum by the contact rollers only. The carrier (16) is connectable to a pressing device for moving and pressing the carrier (16) and the lower drum carried thereby towards and against the upper drum for providing cutting pressure between the upper drum and the lower drum.