Seal-less Mill Head Using Centrifugal Oil Circulation
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Solution Overview
Problem
Dowel-mill head assemblies face issues with lubrication, as grease leads to high operating temperatures and low rotational speeds, while lubricating oil increases maintenance costs due to stringent sealing requirements and consumable seals that need frequent replacement.
Innovation Solution
A seal-less mill head assembly utilizing centrifugal hydrodynamic force to retain and re-circulate lubrication oil, eliminating the need for replaceable seals and reducing maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If grease is used as lubricant, then operating temperature is reduced, but rotational speed is limited and heat dissipation is poor
Solution Approach 1:
The patent uses lubricating oil instead of grease, and implements a hydraulic-like circulation system where oil is pumped through channels in the head assembly to provide continuous lubrication and cooling. This allows the system to achieve both acceptable temperature control and high rotational speeds by replacing the static grease lubrication with a dynamic oil circulation system.
2Speed
If lubricating oil is used as lubricant, then rotational speed is increased and heat dissipation is improved, but sealing requirements become more stringent and maintenance costs increase
Solution Approach 1:
The patent extracts and eliminates the sealing components from the mill head assembly. By using open oil circulation channels that allow oil to flow freely through the bearing areas and then drain back to the reservoir, the design removes the need for seals that would otherwise require periodic replacement, thereby reducing maintenance costs despite using lubricating oil.
Solution Approach 2:
The system implements self-service through automatic oil circulation. The oil pump continuously circulates oil through the head assembly, and gravity or pressure differential causes the oil to drain back to the reservoir, creating a self-sustaining lubrication system that requires no manual seal replacement or intervention.
3Reliability
If contacting seals are used to retain lubricating oil, then lubricant retention is achieved, but seal wear and heat generation from friction occur requiring periodic replacement
Solution Approach 1:
The patent completely removes the contacting seal components from the system. Instead of using lips or seals that contact rotating parts, the design employs open oil circulation channels where oil is retained by the geometry of the channels and the circulation system itself, eliminating wear and friction-related failures associated with traditional seals.
Solution Approach 2:
The patent replaces the mechanical contacting seal system with a fluid dynamics-based retention system. Oil retention is achieved through controlled fluid flow patterns, channel geometry, and pressure differential rather than mechanical contact, substituting a wear-free fluid mechanism for a wear-prone mechanical seal system.
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 allows for increased rotational speeds, improved product quality, and reduced maintenance costs by effectively re-circulating and retaining lubrication oil within the head assembly without the need for conventional seals.
Implementation Method 1
This invention discloses a specific mill head assembly, utilizing centrifugal hydrodynamic force and other properties of fluid dynamics, which directs lubricant flow and retains lubricant without the need for a replaceable (contact-type) seal.
Data Source
AI summary
A mill head assembly apparatus utilizing centrifugal hydrodynamic force to circulate lubrication oil while retaining the lubricant without the need for a replaceable (contact-type) seal, the apparatus comprising a set of stationary components including a trunnion, an oil ring, a bearing-retainer, and a collector ring and rotating components including a housing, a pump ring, and a baffle-ring, front and rear bearing means. The oil ring receives and circulates the lubrication oil to the bearing means, the housing is disposed with a plurality of housing passages to re-circulate the lubrication oil, and the forward and rear rotating interfaces to retain the lubrication oil within the front and rear mill head assembly. Potential lubrication oil leakage is retained and re-circulated back to the collector ring by close-tolerance seal means.