Extension Spindle with Electromagnetic Force Balancing for Small-Bore Drilling

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Solution Overview

Problem

Existing attachment spindle devices for machine tools require manual weight application, leading to disrupted drilling processes and an enlarged mechanical unit that restricts machining space, making it difficult to control the auxiliary spindle device effectively.

Innovation Solution

An attachment spindle device with an electromagnetic actuator that applies a counterbalancing force to the spindle unit, allowing for a compact structure and precise control of the drilling process, enabling constant force application and precise drilling of small bores.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual weight application is used to balance the spindle, then the drilling process can be performed, but the process is repeatedly disrupted and productivity is reduced

Engineering Contradiction:
Improvedrilling process continuityVSAvoidmanual weight application
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent replaces the manual mechanical weight application system with an electromagnetic actuator that automatically applies balancing forces to the auxiliary spindle unit. This substitution eliminates the need for operators to manually add weights during drilling operations, thereby maintaining continuous productivity while achieving the same force balancing function.

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

Solution Approach 2:

The electromagnetic actuator enables the auxiliary spindle device to self-regulate its positioning and force application without requiring manual intervention. The system automatically maintains the desired force balance during drilling operations, allowing the device to service itself rather than requiring external operator input.

Inventive Principle:
Principle #25Self-service

2Area of stationary object

If a mechanical spring unit with weight plates is used to exert force on the spindle, then the spindle can be brought into floating state, but the structure is unnecessarily enlarged and machining space is restricted

Engineering Contradiction:
Improvemachining spaceVSAvoidmechanical unit structure
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent replaces the bulky mechanical spring unit with weight plates with a compact electromagnetic actuator. This substitution achieves the same force application function (bringing the spindle into floating state) while dramatically reducing the structural footprint and increasing the available machining space around the work spindle.

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

Solution Approach 2:

The invention changes the fundamental operating principle from mechanical (spring force with weights) to electromagnetic (actuator force). This parameter change enables the same functional outcome with a more compact structure, as electromagnetic actuators can generate significant force in a much smaller volume compared to mechanical spring systems.

Inventive Principle:
Principle #35Parameter changes

3Extent of automation

If manual weight application is required, then force balancing can be achieved, but control of the auxiliary spindle device is not possible

Engineering Contradiction:
Improvespindle device controlVSAvoidmanual weight application
Core Design Contradiction:
Extent of automationVSEase of operation

Solution Approach 1:

The electromagnetic actuator replaces manual weight application, enabling full automation of the auxiliary spindle device. The actuator can be controlled via electrical signals to precisely adjust force application, positioning, and operation timing, transforming the device from a manual system to an automated, controllable system that can be integrated with the machine tool's control architecture.

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

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

The electromagnetic actuator maintains a constant drilling force, allowing for precise and efficient drilling of small bores, optimizing the drilling process by reducing disruptions and enhancing the machining accuracy and speed.

Implementation Method 1

an electromagnetic actuator (16) for applying a counterbalancing force to the force of the drive (15) on the auxiliary spindle unit (14)

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentEP3817889B1Extension spindle device for use on a machine tool
Publication Date: 2021.12.29 DMG MORI ULTRASONIC LASERTEC GMBH
  • EP3817889B1 patent drawingFigure 1a
  • EP3817889B1 patent drawingFigure 1b
  • EP3817889B1 patent drawingFigure 2a

AI summary

The present invention relates to an extension spindle device for use on a machine tool, comprising a clamping interface (12) for clamping the extension spindle device on a work spindle of the machine tool, an extension spindle unit (14) with a spindle (14a) for driving a drilling bit clamped on the spindle (14a), an actuator (15) for exerting a force on the extension spindle unit (14), and an electromagnetic actuator (16) for exerting a compensation force opposing the force of the actuator 15 on the extension spindle unit (14).