Refiner Blade Element With Variable Width Bars
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Solution Overview
Problem
Existing refiner blade elements experience higher wear rates at the outer edge due to increased circumferential speed, leading to fiber cutting and vibration issues, as the wear rate is double that of the inner edge, causing blade bars to contact and vibrate excessively.
Innovation Solution
The blade element design features wider second blade bars near the outer edge, with a width increase of 10-50% in the longitudinal direction, providing enhanced wear resistance and compensating for the increased wear rate, while maintaining a consistent blade gap profile and reducing vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blade bars have uniform width across the blade element, then manufacturing is simple, but wear resistance at the outer edge is insufficient due to higher circumferential speed
Solution Approach 1:
The blade element implements local quality by varying the width of second blade bars along the radial direction. Blade bars at the outer edge (higher circumferential speed region) are made wider than those at the inner edge, creating non-uniform local properties that match the local wear conditions. This resolves the contradiction by making the blade element structure more complex only where needed (outer edge) to improve wear resistance, rather than making the entire structure uniformly complex.
2Duration of action of moving object
If blade bars at the outer edge wear faster, then operational time is extended, but blade bars come into contact causing fiber cutting and increased vibration
Solution Approach 1:
The patent applies local quality by making second blade bars wider at the outer edge where circumferential speed and wear rate are higher. This local structural enhancement prevents excessive wear accumulation in the critical outer region, maintaining adequate blade bar spacing throughout operation. Consequently, blade bars do not come into contact, avoiding fiber cutting and vibration issues while extending operational time.
Solution Approach 2:
The blade element design incorporates preliminary action by pre-compensating for future wear through the non-uniform blade bar width configuration. Before wear occurs, the outer edge blade bars are already made wider to account for the higher wear rate they will experience. This preliminary structural adjustment ensures that even after significant operational wear, the blade bars maintain sufficient spacing to prevent contact and harmful effects.
Data Source
Figure 1~4
Figure 3
AI summary
A blade element (12) for a refiner (10, 11) for refining fibrous material comprises an inner edge (13) and an outer edge (14) and first blade bars (18) and first blade grooves (19) therebetween, the first blade bars and the first blade grooves extending towards the outer edge of the blade element. At top surfaces of the first blade bars there are second blade bars (20) and second blade grooves (21) therebetween. At least some of the second blade bars (20) lying on the outer end portion (12b) of the blade element (12) have a width which is larger than a width of second blade bars (20) lying on the inner end portion (12a) of the blade element (12) and/or is increasing in direction towards the outer edge (14) of the blade element (12).