Spindle Head Friction Torque Limiting Mechanism
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Solution Overview
Problem
The existing spindle head systems in machine tools are prone to deformation due to unexpected movements caused by programming errors or external disturbances, leading to potential collisions between the spindle and processing tools or workpieces, which can result in significant impact forces and damage.
Innovation Solution
The spindle head incorporates a rotation driving device and a clamping device with a bolt group system that utilizes friction forces to prevent relative rotation between components, ensuring the spindle remains within permissible torque limits during processing, thereby absorbing collision energy through relative rotation and reducing the risk of deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the spindle head is rigidly connected to prevent any relative movement, then processing precision is improved, but the spindle becomes vulnerable to deformation during collision accidents
Solution Approach 1:
The connection between rotating members changes from static rigid connection to dynamic conditional connection. During normal operation, friction force maintains rigid connection for precision. During collision, when torque exceeds friction threshold, relative rotation is permitted to absorb impact energy and protect the spindle from deformation.
Solution Approach 2:
The friction force parameter is carefully controlled to create a torque threshold. This parameter change enables the connection to transition between two states: rigid connection under normal torque (maintaining precision) and flexible connection under excessive torque (preventing deformation). The friction coefficient and normal force are optimized to distinguish between normal operational torque and collision torque.
2Strength
If bolt groups are used to fasten rotating members, then structural strength is improved, but the system becomes vulnerable to damage from excessive collision forces
Solution Approach 1:
The friction-based connection acts as a pre-designed cushioning mechanism. Instead of relying on bolt groups to absorb collision energy (which could cause damage), the system is designed so that friction force yields first during collision, allowing relative rotation that dissipates impact energy before it reaches the bolt groups and spindle, thereby protecting the fastening structure from excessive forces.
3Ease of operation
If friction force is used to prevent relative rotation, then ease of operation is improved, but the connection may fail under excessive torque loads
Solution Approach 1:
The potential weakness of friction-based connections (inability to transmit excessive torque) is converted into a protective feature. The friction limit, which could be seen as a weakness, becomes a safety mechanism that prevents torque transmission beyond safe levels during collision, protecting the spindle while maintaining smooth operation during normal use.
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 effectively restricts deformation of the spindle by managing torque forces within safe limits, preventing damage and maintaining processing precision even during interference accidents, thus enhancing the reliability and accuracy of machine tool operations.
Implementation Method 1
two rotating members that form a rotation transmission mechanism for rotating the spindle and that transmit drive force of the rotation driving device are fastened to each other at respective connection sections by a bolt group and are connected to each other so as to be prevented from rotating relative to each other by friction force resulting from the fastening
Implementation Method 2
Rotation prevention torque based on the friction force is a value greater than torque applied to the connection sections during processing and smaller than torque applied to the connection sections when external force that causes the spindle to deform beyond a permissible range during the rotation of the spindle is applied to the spindle
Data Source
AI summary
In a spindle head for a machine tool in which a spindle (10) to which a tool is mounted is rotated around an axial line of a support shaft (58, 59), two rotating members (9, 58) that form a rotation transmission mechanism for rotating the spindle (10) and that transmit drive force of the rotation driving device (56) are fastened to each other at respective connection sections thereof by a bolt group (301) and are connected to each other so as to be prevented from rotating relative to each other by friction force resulting from the fastening. Rotation prevention torque based on the friction force is a value greater than torque applied to the connection sections during processing and smaller than torque applied to the connection sections when external force that causes the spindle (10) to deform beyond a permissible range is applied to the spindle (10). Therefore, even if the tool or the spindle (10) collides with, for example, a processing tool, the spindle (10) does not become deformed beyond the permissible range.