Variable-Thickness Saddle Frame for Machine Tool Vibration Control
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Solution Overview
Problem
Machine tools with a saddle that supports a tool spindle face challenges in reducing the weight of the saddle to minimize moment of inertia and restraining vibrations that affect machining accuracy.
Innovation Solution
A machine tool design where the saddle's frame portion has varying thickness along a vertical direction, with maximum thickness closer to the upper end, enhancing rigidity and reducing weight, and incorporating guide portions and feeding devices to stabilize the saddle's movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the frame portion is ensured to be large over the entire area in the vertical direction, then the rigidity of the saddle is improved, but the weight of the saddle increases
Solution Approach 1:
The frame portion is designed with non-uniform thickness distribution, making the thickness maximum at positions closer to the upper end portion than the lower end portion. This local quality variation ensures rigidity is enhanced where needed (upper regions experiencing greater vibration) while reducing material usage and weight in less critical areas.
2Weight of moving object
If the weight of the saddle is reduced, then the moment of inertia of the saddle is reduced, but the rigidity of the saddle decreases leading to increased vibration
Solution Approach 1:
By concentrating the frame thickness at specific locations (closer to the upper end), the design achieves optimal vibration control without requiring uniform thickness throughout. This localized reinforcement maintains stability where vibrations occur most intensely while keeping overall weight low for reduced moment of inertia.
Solution Approach 2:
The thickness variation is implemented along the vertical dimension, creating a gradient structure that addresses vibration control in the critical upper region without proportionally increasing weight throughout the entire saddle structure.
Data Source
AI summary
A machine tool includes a bed, a column which is provided on the bed so as to be erected therefrom, a saddle which is a moving body supported by the column, and a tool spindle which is supported by the saddle and rotates a tool around a rotation center axis extending in a Z-axis direction parallel to a horizontal direction. The saddle has a frame portion which is provided so as to surround the tool spindle. The thickness of the frame portion in the Z-axis direction changes along a Y-axis direction parallel to a vertical direction, and becomes maximum at a first position-(Pa) closer to an upper end portion of the frame portion than a lower end portion of the frame portion.