Imaginary Spindle Control for Vibration Cutting in Machine Tools

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Solution Overview

Problem

Conventional machine tools are limited in their ability to perform reciprocating vibration cutting without rotating the spindle, restricting flexibility in machining and requiring vibration frequency to be set based on spindle rotation, which does not allow for vibration cutting without spindle rotation.

Innovation Solution

The machine tool incorporates a control apparatus that allows for reciprocating vibration of the cutting tool and workpiece relative to each other in the feeding direction, with parameters such as the number of rotations and vibration frequency being set and corrected to enable vibration cutting without spindle rotation, using an imaginary spindle concept for software control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If vibration frequency is set based on spindle rotation in conventional machine tools, then the control system can operate at predetermined cycles, but the machine tool cannot perform vibration cutting without rotating the spindle, reducing machining flexibility

Engineering Contradiction:
Improvemachining flexibilityVSAvoidcontrol system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a virtual copy of the spindle rotation concept through the imaginary spindle, allowing the control system to manage vibration frequency independently of actual spindle rotation. The imaginary spindle serves as a software-based model that enables vibration cutting parameters to be set and controlled without requiring physical spindle rotation, thus achieving vibration cutting flexibility while maintaining a relatively simple control architecture.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical dependency between spindle rotation and vibration frequency with a software-based control mechanism. Instead of requiring actual spindle rotation to define vibration parameters, the system uses the imaginary spindle concept to substitute the mechanical relationship with a computational model, allowing independent control of vibration frequency and enabling vibration cutting without spindle rotation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If the control apparatus issues operation instructions at predetermined cycles, then the control system remains simple, but the vibration frequency is limited to values that match the instruction cycle, restricting vibration cutting capabilities

Engineering Contradiction:
Improvevibration frequency rangeVSAvoidparameter control complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent fundamentally changes the parameter relationship between spindle rotation and vibration frequency by introducing the imaginary spindle. This allows vibration frequency to be set as an independent parameter rather than being derived from spindle rotation speed and instruction cycle. The correction means further adjusts these parameters to ensure proper coordination between vibration frequency, number of vibrations per rotation, and instruction cycle, expanding the achievable vibration frequency range while maintaining control simplicity.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If reciprocating vibration is performed without considering vibration frequency constraints, then the cutting tool can vibrate relative to the workpiece, but the vibration may not synchronize properly with spindle rotation, affecting chip separation and cutting quality

Engineering Contradiction:
Improvechip separation qualityVSAvoidparameter coordination complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism through the correction means that monitors and adjusts the relationship between vibration frequency, number of vibrations per imaginary spindle rotation, and actual spindle rotation. This feedback loop ensures that the reciprocating vibration synchronizes properly with the spindle rotation to achieve optimal chip separation, while the imaginary spindle provides a reference framework for maintaining proper phase relationships without requiring complex real-time adjustments.

Inventive Principle:
Principle #23Feedback

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

This configuration allows for flexible machining and vibration cutting without rotating the spindle, enabling smooth cutting and chip separation while increasing machining flexibility by allowing vibration cutting to be performed without spindle rotation.

Implementation Method 1

vibration means configured to reciprocatively vibrate the cutting tool and the workpiece relative to each other in the feeding direction

Methodology Applied
Scientific EffectMechanical vibration: Vibration

Data Source

PatentEP3348351B1Control device for machine tool, and machine tool
Publication Date: 2023.02.08 CITIZEN WATCH CO LTD
  • EP3348351B1 patent drawingFigure 1
  • EP3348351B1 patent drawingFigure 2
  • EP3348351B1 patent drawingFigure 3

AI summary

[Abstract] To provide a control apparatus of a machine tool and the machine tool, which can perform reciprocating vibration in consideration of a vibration frequency, increase flexibility in machining a workpiece, and perform vibration cutting by means of an external spindle and the like without rotating a spindle. A control apparatus (10) of a machine tool (100) and the machine tool (100) include control means (11). The control means (11) includes an imaginary spindle regarded as a spindle (110) for rotating a workpiece W or a cutting tool (130). The control means (11) sets the number of rotations of the imaginary spindle and the number of vibrations of reciprocating vibration during one of the imaginary spindle in accordance with a vibration frequency attributable to a cycle during which an operation instruction can be issued.