Spindle Position Detection Through Ceramic-Bearing Insulation
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Solution Overview
Problem
Cutting apparatuses with ceramic bearings face insulation issues, preventing electrical detection of relative positions between the spindle unit and detecting tool, necessitating complex conduction mechanisms to maintain high precision machining.
Innovation Solution
Incorporating a push rod and mover to move the push rod to a position where it contacts the draw bar and collet chuck, allowing current to be fed through the main shaft to the detecting tool, enabling electrical conduction and position detection with a simple structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a ceramic bearing is used to increase the number of revolutions of the main shaft, then the speed and durability are improved, but the main shaft becomes electrically insulated, making it impossible to electrically detect the relative positions of the detecting tool and the detecting element
Solution Approach 1:
A conductive member is introduced as an intermediary between the detecting tool and the detecting element. This conductive member makes contact with the detecting tool and transmits electrical signals, bypassing the need for the main shaft to be conductive. The intermediary allows electrical detection to function even when the ceramic bearing insulates the main shaft, thus resolving the contradiction between using ceramic for high-speed rotation and maintaining electrical conduction for position detection.
2Reliability
If a complicated device or mechanism is added to ensure conduction of the main shaft, then the electrical detection function is restored, but the device complexity increases
Solution Approach 1:
The conductive member serves as a simple intermediary that restores electrical conduction without adding complex mechanisms. Instead of modifying the ceramic bearing or the main shaft structure, the conductive member makes direct contact with the detecting tool, providing a straightforward solution that maintains simplicity while ensuring reliable electrical detection.
3Speed
If the main shaft is insulated from certain components to use a ceramic bearing, then the high-speed rotation capability is achieved, but it becomes impossible to electrically detect the relative positions without additional complex structures
Solution Approach 1:
The conductive member acts as a mediator that bridges the gap created by the insulated main shaft. It contacts the detecting tool and provides a conduction path that does not require the main shaft to be conductive, thus allowing the ceramic bearing to enable high-speed rotation while the conductive member maintains simple electrical detection capability.
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 solution increases the number of revolutions of the main shaft and ensures conduction while maintaining high precision machining without the need for complex conduction mechanisms.
Implementation Method 1
The bearing is made of a ceramic material. The main shaft is rotatably supported by the bearing.
Implementation Method 2
The conductive member detects contact of the detecting tool with the conductive member upon being brought into electrical conduction with the push rod.
Data Source
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AI summary
A cutting apparatus (10) includes a spindle unit (60) and a controller (48). The spindle unit (60) includes a spindle (62) including a main shaft (65), a collet chuck (67), and a draw bar (68). With a push rod (83) located at a second position (P2) and a detecting tool (6B) gripped by a first end (67A) of the collet chuck (67), the controller (48) controls a current feeder (45) so as to feed a current to the push rod (83) and controls a carriage (38) so as to move the spindle unit (60) in a predetermined direction, bringing the detecting tool (6B) into contact with a conductive element (43). The main shaft (65) provided with a through hole (65H) having the draw bar (68) and the collet chuck (67) inserted therethrough is rotatably supported by first and second bearings (64A) and (64B) each made of a ceramic material.