Chuck Device Nut Alignment via Elastic Tapered Surfaces
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Solution Overview
Problem
Existing chuck devices for machine tools experience non-alignment of the nut relative to the chuck body during high-speed rotation, leading to tool deflection due to centrifugal forces, which cannot be prevented by screwing forces alone, and manufacturing errors in guide portions exacerbate this issue.
Innovation Solution
Incorporating a non-alignment prevention member that allows radial contact between the nut and chuck body through elastic deformation, utilizing tapered surfaces to increase the diameter of the nut or ring member, and providing a fitting portion for relative rotatability to prevent radial movement, thereby maintaining alignment and preventing deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the nut is fastened only by screwing-on force, then the structure is simple, but the nut becomes radially movable relative to the chuck body during high-speed rotation due to centrifugal force
Solution Approach 1:
A non-alignment prevention member is introduced as an intermediary component between the nut and chuck body. This member includes a contact portion that contacts the chuck body and a pressing portion that presses the nut, transferring radial contact force to prevent nut movement while maintaining structural simplicity
Solution Approach 2:
The non-alignment prevention member is divided into distinct functional portions: a contact portion for radial contact with the chuck body, and a pressing portion for applying pressure to the nut. This segmentation allows each portion to be optimized for its specific function while working together to solve the contradiction
2Reliability
If a guide portion is provided to prevent non-alignment, then alignment stability improves, but manufacturing precision requirements increase due to gap fitting errors
Solution Approach 1:
The design changes the approach from precise gap fitting to elastic deformation. The non-alignment prevention member is made elastic so that it deforms under centrifugal force to maintain contact, transforming the requirement from high manufacturing precision to controlled elastic behavior which is less sensitive to manufacturing variations
Solution Approach 2:
The elastic non-alignment prevention member acts as a cushion that anticipates and compensates for centrifugal force effects. By being pre-configured with elastic properties, it automatically adjusts to maintain contact and alignment without requiring extremely precise initial manufacturing tolerances
3Reliability
If the diameter of the guide portion is increased to prevent non-alignment, then alignment stability improves, but the centrifugal force on the nut increases
Solution Approach 1:
The non-alignment prevention member serves as a mediator that allows the nut to maintain alignment without directly increasing its diameter. The contact portion of the mediator contacts the chuck body while the pressing portion maintains pressure on the nut, preventing radial movement without subjecting the nut to excessive centrifugal forces
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 effectively prevents nut non-alignment and tool deflection even at high speeds by utilizing elastic forces and wedging effects, reducing manufacturing costs and part complexity while ensuring machining accuracy.
Implementation Method 1
it is preferable that the contacting force as noted above is produced by elastic deformation of either one of the nut and the chuck body
Implementation Method 2
a tapered surface 103a formed in the collet 103 and a tapered surface 104a formed in the nut 104 are brought into contact with each other... the collet 103 and the nut 104 are brought into contact with each other at the tapered surfaces, thereby to press the collet 103 axially and fasten the collet 103 radially inward
Implementation Method 3
if a centrifugal force is increased by high-speed rotation, the relative movement cannot be prevented only through the screwing-on force
Data Source
Figure 1a~2
Figure 3~5
Figure 6~7
AI summary
In order to provide a chuck device for suppressing non-alignment of a nut relative to a chuck body and preventing deflection of a tool when a machine tool is rotated even at high speed, the chuck device includes: a chuck body 2 having a tapered hole 20 at a front end portion thereof, the chuck body 2 being fixed directly or indirectly to a rotational spindle of the machine tool; a collet 3 capable of being reduced in diameter and inserted into the tapered hole 20 for holding the tool T; and a nut 4 that can be screwed to the chuck body 2 for fastening the collet 3. A non-alignment prevention member is provided for suppressing relative movement by bringing the nut 4 into radial contact with the chuck body 2 even when the spindle of the machine tool is rotated. The non-alignment prevention member includes a first nut rear end side tapered surface 4a formed in an inner circumferential surface or an outer circumferential surface of the nut 4 at a farther rear end side than a screw portion 40, and a chuck body side tapered surface 2a formed in the chuck body 2 for coming into contact with the first nut rear end side tapered surface 4a when the nut 4 is screwed up.