Spindle Drawbar Sealing for Low-Friction Pull Stud Clamping
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Solution Overview
Problem
The existing spindle device experiences reduced durability of the sealing member due to high friction when the pull stud is inserted or removed, leading to coolant fluid adherence on the tapering surface, which in turn reduces tool-holding rigidity.
Innovation Solution
A spindle device design featuring a pull stud with a flange and an inclined portion that reduces in diameter, combined with a sealing member fixed to the draw bar's flow path wall, minimizing friction and improving durability by contacting the inclined surface of the pull stud.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing member (O-ring) is provided between the flange and the draw bar to prevent coolant leakage, then sealing performance is improved, but friction increases when the pull stud is inserted or removed
Solution Approach 1:
The sealing function is segmented from the pull stud and assigned to a dedicated sealing member fixed to the draw bar. This allows the sealing member to remain stationary while the pull stud moves, reducing friction during insertion and removal operations while maintaining effective sealing.
Solution Approach 2:
The sealing member acts as an intermediary element between the pull stud and the draw bar. It provides the sealing function without being directly attached to the moving pull stud, thereby mediating the interaction and reducing friction during operational movements.
2Reliability
If the pull stud slides against the sealing member during insertion and removal, then sealing is maintained, but durability of the sealing member reduces
Solution Approach 1:
The system is segmented such that the sealing member is a separate, stationary component fixed to the draw bar, while the pull stud is the moving component. This segmentation allows the sealing member to maintain its sealing function without undergoing repeated sliding motions, thereby preserving its durability.
Solution Approach 2:
Instead of attaching the sealing member to the moving pull stud (which would cause friction wear), the sealing member is invertedly attached to the stationary draw bar. This inversion of the attachment relationship eliminates the relative sliding motion between the sealing member and the pull stud during insertion and removal, significantly improving sealing member durability.
3Ease of operation
If the sealing member durability reduces, then friction decreases initially, but coolant fluid adheres to the tapering surface and tool-holding rigidity reduces
Solution Approach 1:
The sealing member is designed to maintain effective sealing throughout its service life by eliminating harmful sliding friction. This allows the system to skip the degradation phase where coolant leakage would occur, maintaining consistent tool-holding rigidity without the need for frequent sealing member replacement.
Solution Approach 2:
The invention avoids the need for frequent replacement of expensive sealing members by designing a system where the sealing member remains durable throughout its service life. The stationary mounting of the sealing member eliminates the sliding friction that would otherwise cause premature wear and require replacement, making the sealing solution more cost-effective in the long term.
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 significantly reduces friction during pull stud insertion and removal, enhances sealing member durability, and prevents coolant fluid adherence, thereby maintaining tool-holding rigidity and allowing for a potentially smaller spindle size.
Implementation Method 1
friction caused by sliding of the pull stud against the sealing member (O-ring) becomes large
Data Source
AI summary
A spindle device includes: a spindle: a drawbar provided in a through-hole in the spindle; a plurality of balls that clamp or unclamp a pull stud in response to the drawbar moving forward or backward; and a seal member fixed to a wall surface that forms a flow path in the drawbar, so as to come into contact with an inclined surface of the inclined section of the pull stud clamped by the plurality of balls.