Tool Holder Coolant Ejection via Gap Nut and Bearing
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Solution Overview
Problem
Conventional cutting oil supply methods for machine tools, such as external oil feeding and cutter through methods, face challenges in efficiently delivering coolant to the workpiece due to interference, centrifugal force, and the need for internal oil feeding holes, which are costly and difficult to implement, especially in machining centers with automatic tool changers.
Innovation Solution
A tool holder design that includes a shank portion, a tool attachment portion, a cover with a tubular wall and ejection port, and a bearing to prevent co-rotation, allowing coolant to be ejected from a position close to the workpiece without requiring internal oil feeding holes, effectively suppressing centrifugal force and enabling precise coolant delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cutter through method is used to supply cutting oil through an internal oil feeding hole, then the cutting oil can reach the workpiece, but the blade portion cannot be lubricated and cooled efficiently and the tool becomes expensive and difficult to manufacture
Solution Approach 1:
The invention extracts the oil feeding hole from the tool body and relocates it to the tool holder. The tool holder includes a through hole that opens at the tip end, allowing cutting oil to be supplied externally without requiring internal oil feeding holes in the tool itself. This resolves the contradiction by maintaining reliable coolant supply while eliminating the manufacturing complexity and cost associated with internal oil feeding holes in the tool.
Solution Approach 2:
The tool holder acts as an intermediary device between the cutting oil supply system and the tool. It provides the through hole for oil supply and includes a gap nut that creates a gap through which cutting oil is ejected onto the tool's outer peripheral surface. This intermediary structure enables efficient lubrication and cooling of the blade portion without requiring modifications to the tool itself.
2Device complexity
If the external oil feeding method is used with a fixed nozzle, then the nozzle structure is simple, but the cutting oil may be blocked by the workpiece and cannot reach the workpart precisely
Solution Approach 1:
The invention makes the cutting oil ejection position dynamic by attaching the gap nut to the tip end of the tool holder, which rotates with the tool. This allows the ejection position to follow the tool's rotation and movement, ensuring precise delivery of cutting oil to the workpart without the need for a complex externally movable nozzle system. The gap between the gap nut and tool outer periphery provides a consistent ejection point regardless of tool rotation.
Solution Approach 2:
The invention merges the cutting oil supply function with the tool holder structure. The through hole in the tool holder and the gap nut are integrated into the tool holder assembly, combining the coolant delivery mechanism with the tool mounting structure. This eliminates the need for a separate external nozzle system while maintaining precise coolant delivery capability.
3Productivity
If the tool rotates at high speed, then productivity increases, but centrifugal force prevents cutting oil from reaching the workpiece
Solution Approach 1:
The invention applies preliminary action by ejecting cutting oil through the gap between the gap nut and tool outer periphery before the tool rotates at high speed. The cutting oil is supplied onto the tool's outer peripheral surface in advance, allowing it to reach the blade portion and workpart effectively before centrifugal force becomes dominant. This preliminary coolant application ensures continuous lubrication and cooling even at high rotation speeds.
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 tool holder ensures efficient and precise coolant supply to the workpiece, preventing bearing seizure at high speeds and facilitating automatic tool exchange, while eliminating the need for internal oil feeding holes, thus enhancing machining stability and reducing costs.
Implementation Method 1
a bearing provided between the tubular wall of the cover and the tool attachment portion
Implementation Method 2
effectively suppressing centrifugal force and enabling precise coolant delivery
Data Source
AI summary
A tool holder includes: a shank portion gripped by a main shaft; a tool attachment portion having an insertion port into which a tool is inserted in a tip end surface thereof; a cover having a tubular wall that covers an outer periphery of the tool attachment portion and a bottom surface that covers the tip end surface of the tool attachment portion; a bearing provided between the tubular wall of the cover and the tool attachment portion; and a stopper that prevents the cover from co-rotating with the tool attachment portion. A through hole penetrated by the tool and an ejection port disposed on a periphery of the through hole in order to eject the coolant toward the tool are provided in the bottom surface of the cover.