Multi-Spindle Head Indexing With Independent Spindle Rotation
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Solution Overview
Problem
Mechanical-type multi-spindle machine tools, such as Davenport® five-spindle automatic screw machines, lack independent spindle assembly rotation, precise head positioning without expensive encoders, and zero-backlash tool slides, limiting their accuracy and performance.
Innovation Solution
The implementation of a multi-spindle machine tool design featuring independently rotating spindle assemblies driven by motors and ring gears, a Geneva indexing mechanism with proximity sensors for angular position determination, and rolling-element bearings for precise head mounting, along with zero-backlash tool slides using ball screws and linear rails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mechanical-type multi-spindle machine tool uses a conventional indexing mechanism with spindles rigidly mounted on the head, then the structure is simple and cost-effective, but the spindles cannot rotate independently and positioning precision is limited
Solution Approach 1:
The machine tool system is segmented into independently controllable spindle assemblies, each with its own motor and drive mechanism. This allows each spindle to rotate independently while maintaining precise positioning, resolving the contradiction between simplicity and precision by dividing the system into modular functional units.
Solution Approach 2:
The spindle assemblies are designed with dynamic rotation capabilities, allowing them to rotate independently at variable speeds while maintaining precise angular positioning. This dynamic flexibility enables high positioning precision without requiring a completely complex rigid mounting structure.
2Measurement precision
If expensive encoder systems are installed on the head for precise angular position determination, then positioning accuracy improves, but the system cost increases significantly
Solution Approach 1:
The patent replaces expensive electronic encoder systems with a mechanical sensing approach using proximity sensors that detect the angular position of the head through mechanical features. This substitution maintains measurement precision while dramatically reducing system cost and complexity.
Solution Approach 2:
The invention uses simple, inexpensive proximity sensors and mechanical indexing features instead of expensive, complex encoder systems. These simpler components achieve sufficient positioning precision at a fraction of the cost, making the system more economically viable.
3Manufacturing precision
If traditional tool slides with mechanical backlash are used, then the structure is simple, but positioning accuracy and repeatability deteriorate
Solution Approach 1:
The patent replaces traditional mechanical slide mechanisms with ball screw drives and linear rails that eliminate backlash through their inherent design. This substitution maintains structural simplicity while dramatically improving positioning accuracy and repeatability by eliminating the backlash problem inherent in conventional mechanical slides.
4Adaptability or versatility
If all spindle assemblies are rigidly coupled to rotate together with the head, then the structure is simple, but independent spindle rotation and differential speed control are lost
Solution Approach 1:
The spindle drive system is segmented into independent motor-spindle units, each capable of autonomous rotation. This segmentation enables differential speed control and independent operation of each spindle while maintaining a relatively simple overall structure through modular design.
Solution Approach 2:
Each spindle assembly is designed as a universal module that can rotate independently, be driven by its own motor, and maintain precise positioning. This multi-functionality allows each spindle to operate autonomously while the overall system maintains structural simplicity through repetition of the same modular unit.
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
Enables independent spindle rotation, precise head positioning without expensive encoders, and zero-backlash tool movement, enhancing the accuracy, productivity, and service life of mechanical-type multi-spindle machine tools.
Implementation Method 1
a plurality of ring gears mounted on the head and engaging a respective one of the spindle assemblies, each ring gear being driven by a respective one of the motors
Implementation Method 2
at least one rolling-element bearing acting between the head and frame such that the position of the head relative to the frame may be controlled at each of the index positions
Implementation Method 3
zero-backlash tool slides using ball screws and linear rails
Implementation Method 4
zero-backlash tool slides using ball screws and linear rails
Data Source
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.