Toolholder Assembly Non-Circular Shank Quick-Change Locking
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Solution Overview
Problem
Existing tooling systems for machine tools require significant downtime for changing damaged or worn-out cutting tools due to the need to remove and replace the entire toolholder, and there is a need for improved systems with increased strength and durability.
Innovation Solution
A toolholder assembly with a non-circular cross-section toolholder shank and base member, a canister with locking passageways, a lock rod with depressions, and a locking member that allows for quick and secure attachment and detachment, providing high clamping and torsional stiffness through tri-lobe configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the entire toolholder is removed and replaced when the cutting tool needs to be replaced, then the cutting tool can be changed, but the machine downtime increases significantly
Solution Approach 1:
The toolholder assembly is segmented into a toolholder portion and a base member portion that can be quickly disconnected and reconnected. The quick-change mechanism allows the toolholder to be separated from the base member without removing the entire assembly, enabling rapid tool replacement while maintaining the structural integrity and positioning accuracy of the base member.
Solution Approach 2:
The locking and unlocking mechanisms are pre-positioned and ready for immediate action. The quick-change system includes pre-aligned locking apertures, locking balls, and actuating elements that enable the toolholder to be secured or released with a single motion, eliminating the need for multiple adjustment steps during tool changes.
2Loss of time
If a quick change tooling system is used to reduce downtime, then tool change time decreases, but the strength and durability of the tooling system may be compromised
Solution Approach 1:
The locking mechanism employs an asymmetric design with locking balls that engage into specifically shaped locking apertures. This asymmetric geometry provides mechanical advantage and ensures positive locking with high strength, while the actuating element provides symmetric control for easy operation. The non-circular cross-section of the toolholder shank also contributes to asymmetric engagement that enhances torsional stiffness.
Solution Approach 2:
Spherical locking balls are used to engage with the locking apertures, providing point contact that concentrates locking forces and ensures reliable engagement. The spherical shape allows for self-alignment and smooth transition between locked and unlocked states while maintaining high contact strength during the locked position.
3Strength
If a locking mechanism with multiple components is used to increase strength, then the tooling system becomes more durable, but the device complexity increases
Solution Approach 1:
The locking mechanism merges multiple functions into integrated components. The actuating element simultaneously performs the functions of unlocking the locking balls, retracting the lock rod, and positioning the toolholder for removal. The locking balls serve both as locking elements and as indicators of the locked state. This merging reduces the number of separate components while maintaining high clamping force and torsional stiffness.
4Reliability
If a locking mechanism with multiple components is used to increase durability, then the tooling system becomes more reliable, but the device complexity increases
Solution Approach 1:
The locking mechanism is designed to be self-actuating and self-locking. When the actuating element is moved to the locked position, it automatically drives the lock rod forward to engage the locking balls with the locking apertures, securing the toolholder without requiring additional adjustment or verification steps. The geometry of the locking apertures and locking balls ensures that once engaged, the connection maintains its integrity under cutting forces without additional active control.
Data Source
AI summary
A toolholder assembly includes a toolholder having a toolholder shank with a non-circular cross-section, a base member having a bore with a non-circular cross-section that receives the toolholder shank, a canister positioned in the base member, a lock rod positioned in the canister, a locking ball for cooperating with the lock rod, the canister and/or the toolholder shank and an actuating element configured for cooperation with the lock rod for moving the lock rod between a locked position and an unlocked position.