Multi-Spindle Tool Post for Masked Tool Changes and Low Inertia
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Solution Overview
Problem
Existing multi-spindle tool posts for numerically-controlled machine tools are not entirely satisfactory as they do not completely mask tool change times, require significant energy for simultaneous tool rotation, and are bulky, leading to high moments of inertia and collision risks, especially when machining micromechanical parts.
Innovation Solution
A tool post design featuring a rotatably movable head with independently servo-controlled tool-holder spindles, allowing for masked acceleration and deceleration phases during tool changes, reduced energy consumption, and increased compactness by optimizing spindle arrangement and orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If all tools are driven in rotation simultaneously to mask tool change times, then tool change time is reduced, but energy consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-accelerating the standby spindle to the target rotational speed before it becomes the active tool. This allows the tool change to be completely masked as the accelerated spindle is already ready to machine immediately upon becoming active, eliminating any tool change downtime while avoiding the need to accelerate all spindles simultaneously, thus reducing energy consumption.
2Weight of moving object
If multi-spindle tool posts are designed to be compact, then moment of inertia is reduced, but the risk of collision between fitting and tools increases
Solution Approach 1:
The patent applies segmentation by controlling each spindle independently with individual motors, allowing spindles to be positioned at different angular locations around the rotation axis. This enables a compact tool post design with reduced moment of inertia while maintaining safe distances between tools and the fitting, thereby reducing collision risk despite the compact configuration.
3Speed
If tool posts are designed with high rotational speed capability, then machining precision is improved, but the complexity of motion transmission increases
Solution Approach 1:
The patent replaces the traditional mechanical motion transmission system with individual electric motors for each spindle. This substitution eliminates complex gear trains and motion transmission chains, allowing each spindle to independently achieve high rotational speeds (up to 80,000 rpm) without the complexity and limitations of mechanical transmission systems.
4Loss of time
If individual spindle control is implemented, then tool change time is reduced, but device complexity increases
Solution Approach 1:
The patent applies universality by using identical electric motor and control unit configurations for each spindle. This standardized multi-functional approach allows each spindle to independently perform acceleration, deceleration, and positioning operations, enabling rapid tool changes while managing complexity through modular, interchangeable components rather than customized systems for each spindle.
Data Source
AI summary
A tool post including a body extending according to an axis A-A, the latter including, at one of its ends, a base for fastening to a numerically-controlled machine tool and, at the other end, a head movable in rotation, the head including at least two tool-holder spindles, each being intended to receive a cutting tool in engagement, the spindles occupying, depending on the angular position of the head, a working position in which they are intended to carry out a machining operation on a workpiece held in position in a fitting or a standby position in which they are withdrawn from the workpiece, each of the spindles being configured to be controlled independently of the other in order to immobilise or drive in rotation the cutting tool carried thereby, irrespective of the position it occupies.