Three-Axis Grinding Control for Eccentric and Concave Workpieces

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Solution Overview

Problem

Small grinding tools struggle to efficiently process eccentric and concave shapes due to restricted access and uneven tool movement, leading to vibrations and imprecise machining, while large tools are not suitable for all applications and may cause acceleration issues.

Innovation Solution

The method involves calculating and moving a tool along three axes (Xm, Cm, and Ym) to ensure constant Cm axis speed and uniform tool movement, allowing a small tool to reach all positions on the workpiece, including eccentric and concave shapes, by calculating the Ym axis coordinate and selecting the appropriate solution based on tool placement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a small tool is used to process eccentric shapes, then the tool can access all positions on the workpiece, but the Cm axis velocity changes continuously and inverts direction causing vibrations and imprecise machining

Engineering Contradiction:
Improvetool accessibility to all workpiece positionsVSAvoidmachining precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The invention introduces a third axis Ym perpendicular to both the rotation axis Cm and the tool movement axis Xm. This dimensional addition allows the tool to reach all positions on eccentric and concave workpieces while maintaining constant Cm axis speed, eliminating the need for velocity inversion and direction changes that cause vibrations.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The system dynamically calculates and adjusts the tool position coordinates (Xm, Cm, Ym) based on the workpiece geometry and desired contour. The real-time coordinate calculation enables the tool to adapt its position while maintaining constant rotation speed, avoiding the dynamic instability caused by continuous acceleration and deceleration.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If a big tool is used to reduce vibrations, then machining precision improves, but concave shapes cannot be machined completely

Engineering Contradiction:
Improvemachining precisionVSAvoidability to machine concave shapes
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

By adding the Ym axis dimension, the system enables small tools to access concave regions that are inaccessible to big tools. The additional degree of freedom allows the tool to approach the workpiece from different spatial directions, completing the machining of concave shapes without requiring tool size increase.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The system applies local quality by using a small tool that can access specific regions (concave shapes) while the multi-axis coordination ensures precise control at each local position. Each point on the workpiece surface is machined with appropriate tool positioning, maintaining precision without requiring a uniformly large tool.

Inventive Principle:
Principle #3Local quality

3Device complexity

If the tool moves only along the Xm axis, then the machine structure is simple, but eccentric shapes cannot be reached in some positions

Engineering Contradiction:
Improvemachine structure simplicityVSAvoidtool accessibility to eccentric positions
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The invention adds the Ym axis to the existing Xm and Cm axes, creating a three-axis coordination system. This minimal dimensional addition enables the tool to reach all positions on eccentric workpieces while maintaining relatively simple machine structure compared to more complex multi-axis systems.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Adaptability or versatility

If the Cm axis speed varies to reach all positions, then tool accessibility improves, but vibrations increase due to continuous acceleration and deceleration

Engineering Contradiction:
Improvetool accessibility to all positionsVSAvoidvibrations
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The Ym axis provides an additional pathway for tool movement, allowing the tool to reach all workpiece positions without requiring Cm axis velocity variations. The constant Cm speed combined with coordinated Ym movement eliminates continuous acceleration and deceleration, reducing vibrations and harmful effects on the workpiece and machine.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3913447A1Processing machine and method for operating a processing machine
Publication Date: 2021.11.24 NUM IND ALLIANCE
  • EP3913447A1 patent drawingFigure 1
  • EP3913447A1 patent drawingFigure 2~3
  • EP3913447A1 patent drawingFigure 4

AI summary

A Method for operating a processing machine (1), wherein a workpiece (5) is rotated in the processing machine (1) along an axis of rotation (Cm) and a tool (2; 6; 22) for processing the workpiece (5) is moved along a first axis (Xm) that is perpendicular to the axis of rotation (Cm) and a second axis (Zm) that is parallel to the axis of rotation (Cm). During operation the coordinates of a contact point (P) between the tool and the workpiece (5) with respect to the axis of rotation (Cm), the first axis (Xm)and a third axis (Ym) that is perpendicular to the first axis (Xm) and the axis of rotation (Cm) is calculated. The tool is the moved along the three axes according to the calculated coordinates. (Fig. 1)