Multi-Spindle Machine Head Positioning and Independent Spindle Control
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Solution Overview
Problem
Mechanical-type multi-spindle screw machines, such as Davenport ®< five-spindle automatic screw machines, lack independent spindle assembly rotation, precise head positioning, cost-effective angular position determination without encoders, and zero-backlash tool slides, limiting their accuracy and performance.
Innovation Solution
The implementation of a multi-spindle machine tool with independently rotating spindle assemblies driven by motors and ring gears, a low-cost sensor apparatus using proximity sensors for angular position determination, precise head mounting with rolling-element bearings, and zero-backlash tool slides, allowing for independent spindle control and precise workpiece manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical-type multi-spindle screw machine uses a single motor with gear train to rotate all spindle assemblies simultaneously, then the device complexity is reduced, but the spindle assembly independence and manufacturing precision deteriorate
Solution Approach 1:
The patent divides the single motor-driven system into multiple independent motor-spindle units. Each spindle assembly is equipped with its own motor and ring gear, allowing independent rotation and speed control. This segmentation enables each spindle to operate autonomously, improving adaptability and versatility while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
The patent introduces dynamic control capabilities by allowing each spindle assembly to rotate at independently variable speeds and directions. The ring gears mounted at different axial positions on the head enable flexible speed matching for each spindle, transforming the static synchronized rotation system into a dynamic, adaptable system that can respond to different machining requirements.
2Measurement precision
If encoders are used for angular position determination of the head, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent introduces an intermediary mechanical indexing mechanism that provides precise angular positioning without requiring electronic encoders. The indexing mechanism with defined stop positions acts as a mediator between the motor drive and the head rotation, providing repeatable angular positioning through mechanical means. This approach maintains measurement precision while avoiding the complexity and cost of encoder systems.
Solution Approach 2:
The indexing mechanism is designed to self-limit and self-position the head at precise angular intervals through mechanical stops and guides. The system uses its own mechanical structure to determine and maintain angular position, eliminating the need for external sensing systems like encoders. This self-service approach reduces device complexity while maintaining positioning precision.
3Device complexity
If traditional tool slides are used in the machine tool, then the device complexity is reduced, but the manufacturing precision deteriorates due to backlash
Solution Approach 1:
The patent replaces traditional mechanical tool slides with a robotic end effector system. The robotic arm with controlled end effector eliminates the mechanical slide mechanism entirely, substituting electronic control and robotic positioning for mechanical sliding contacts. This substitution eliminates backlash inherent in mechanical slides while providing precise tool positioning through servo control, improving manufacturing precision without significantly increasing overall device complexity.
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
Enhances spindle assembly independence, improves head positioning accuracy, reduces costs by eliminating encoder reliance, and provides zero-backlash tool movement, thereby increasing the machines' accuracy, productivity, and service life.
Implementation Method 1
The head is mounted on the frame for rotation about the head axis by means of rolling-element bearings
Implementation Method 2
a sensor apparatus including a plurality of proximity sensors mounted on the frame and arranged to face toward the driven gear of the indexing apparatus
Implementation Method 3
A plurality of ring gears are mounted on the head at various axially-spaced locations and are respectively arranged to rotate associated ones of the spindle assemblies
Implementation Method 4
The collet has a plurality of fingers that extend forwardly from a body. These fingers have angularly-segmented outwardly- and rearwardly-facing frusto-conical cam surfaces that engage the inwardly-facing cam surface on the associated outer spindle.
Data Source
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Figure 4
Figure 5~6
AI summary
The present invention provides certain additional improvements for such mechanical-type multi-axis machine tools. These improvements include: (1) permitting the spindles to be rotated about their respective axes relative to the member independently of one another, (2) providing a low-cost, and yet highly-effective, sensor apparatus for determining the angular position of the member relative to the frame without the use of an expensive encoder or the like, (3) mounting the rotatable member more precisely relative to the frame, and (4) providing a zero-backlash tool slide on the frame for imparting an action to a workpiece.