Machining Toolholder With Segmented Horn And Piezoelectric Actuator
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Solution Overview
Problem
Conventional rotary type ultrasonic vibration assisted machining devices face issues with unstable connections, stress accumulation, assembly errors, friction-induced abrasion, and difficulty in achieving high vibration amplitudes, leading to reduced processing precision and tool longevity when working with hard and brittle materials.
Innovation Solution
A machining toolholder design featuring a body with a center through hole, a horn with coaxial sections for improved stability, a piezoelectric actuator for controlled vibration, and an induction module for efficient energy supply, along with a counter weight and sealing members to manage stress and friction, ensuring effective resistance to stress and maintaining processing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the conventional horn simply utilizes a top surface to engage with the bottom of the body, then the structure is simple, but the connection between the horn and the body is unstable and rotation bias occurs easily
Solution Approach 1:
The horn is divided into multiple sections (first section, second section, third section) with different functions. The first section engages with the body through a center through hole, the second section is the vibration amplification zone, and the third section engages with the tool. This segmentation allows each part to be optimized for its specific function, improving overall connection stability while maintaining structural efficiency.
Solution Approach 2:
The first section of the horn is inserted into the center through hole of the body, creating a nested configuration. This nesting provides precise positioning and stable engagement between the horn and body, preventing rotation bias while maintaining a compact structure.
2Power
If the piezoelectric actuator is installed on the horn to amplify vibration, then the vibration amplification is achieved, but stress accumulates on the joint between the body and the horn, causing cracks after long-time vibration
Solution Approach 1:
The piezoelectric actuator is extracted from the conventional position on the horn and relocated to be driven directly by the spindle through the body. This separation removes the stress accumulation point at the horn-body joint, as the actuator is now independently mounted and driven, eliminating the stress concentration that led to cracking.
Solution Approach 2:
The body serves as an intermediary structure that transmits vibration from the piezoelectric actuator to the horn without creating stress concentration at the horn-body joint. The center through hole design allows the actuator to be positioned such that the body mediates the force transmission, distributing stress more evenly.
3Power
If the vibration antinode is located at the joint between the tool and the terminal end of the horn, then maximum vibration amplitude is achieved at the processing end, but the joint bears maximum friction force causing abrasion or deformation
Solution Approach 1:
The horn is segmented into multiple sections with the vibration antinode positioned at the boundary between the second and third sections, not at the tool joint. This segmentation allows the third section to act as a transition zone that reduces friction at the tool joint while maintaining high vibration amplitude at the processing end through the vibration amplification geometry of the second section.
Solution Approach 2:
Different sections of the horn have different geometries optimized for their specific functions. The second section has a geometry that amplifies vibration, while the third section is designed to reduce friction at the tool joint. This local quality optimization allows high vibration amplitude at the processing end without proportionally high friction at the tool joint.
4Ease of manufacture
If the conventional device is constituted by a plurality of mechanical components, then the device can be assembled, but assembling errors accumulate and result in rotation runout of the spindle
Solution Approach 1:
The nested configuration of the first horn section within the body's center through hole provides self-aligning features that reduce the impact of assembling errors. The nested structure naturally positions components coaxially, minimizing rotation runout even when minor assembly variations occur.
Solution Approach 2:
The horn sections are designed with consistent coaxial geometry and the body features a precisely machined center through hole that maintains uniform clearance. This homogeneity in the mechanical interfaces reduces the accumulation of assembling errors and minimizes rotation runout.
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 toolholder provides enhanced stiffness and connection stability, effectively resisting stress and improving processing precision, while preventing resonance frequency drift and extending tool life by optimizing vibration distribution and reducing friction-induced wear.
Implementation Method 1
the vibration generated by the piezoelectric actuator, can be amplified by the horn and then transmitted to the tool
Implementation Method 2
the vibration generated by the piezoelectric actuator, can be amplified by the horn and then transmitted to the tool
Data Source
AI summary
A machining toolholder including a body, a horn and a piezoelectric actuator is disclosed. The body includes a center through hole extending in the axial direction therein. The center through hole includes a first hole section and a second hole section. The horn includes a first section and a second section which are disposed coaxially and connected with each other. Part of the first section is slidably inserted into the first hole section. The second section is connected to the body and engaged with a tool. Part of the surface of the second section contacts with a wall surface of the second hole section. The piezoelectric actuator fits around the horn and is controllable to drive the tool to vibrate. With this design, the machining toolholder could have good stiffness and connection stability, and could resist to the stress effectively.