Machine Tool Optical Alignment for Precise Workpiece Positioning

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Solution Overview

Problem

Current machine tool systems, particularly milling machines, face inaccuracies and require user intervention for tool changes due to the need for precise workpiece positioning and tool alignment, especially when handling diverse workpieces and tools.

Innovation Solution

A system utilizing a spatially fixed optical sensor with a detection range overlapping the workpiece's motion path, allowing for precise detection of the workpiece's edges and coordinates, enabling accurate alignment and tool selection through code identification, and performing coordinate transformations for precise machining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If contact method is used to determine workpiece position, then determination can be made on basis of machine current rise, but accuracy is comparatively low and abrasion is produced

Engineering Contradiction:
Improveworkpiece position determination accuracyVSAvoidabrasion
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical contact-based detection method with an optical detection system. A camera captures images of the workpiece, and image processing algorithms determine the workpiece position and orientation without physical contact. This substitution eliminates abrasion while significantly improving measurement precision through non-contact optical measurement.

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

Solution Approach 2:

The patent creates an optical copy (image) of the workpiece using a camera. Instead of physically contacting the workpiece to detect its position, the system captures an image and processes it to determine precise position and orientation information. This copying approach enables accurate measurement without physical interaction that would cause wear.

Inventive Principle:
Principle #26Copying

2Extent of automation

If identification means are used for workpiece-program assignment, then workpiece identification is enabled, but user intervention is still required for tool changing

Engineering Contradiction:
Improveworkpiece-program assignment automationVSAvoidtool changing operation
Core Design Contradiction:
Extent of automationVSEase of operation

Solution Approach 1:

The patent implements a self-service system where the camera detects both workpiece identification codes and tool identification codes. The control unit automatically matches the detected workpiece with the appropriate program and selects the correct tool based on the detected tool code, eliminating the need for manual tool changing. The system serves itself by automatically coordinating workpiece identification, program selection, and tool selection.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The camera system performs multiple functions: it identifies the workpiece type, determines workpiece position and orientation, and identifies the tool being used. This multi-functional detection system replaces multiple separate systems, enabling complete automation of workpiece-program assignment and tool selection through a single integrated optical detection approach.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 approach enables high-accuracy machining with reduced user intervention by accurately determining the workpiece's position and selecting the appropriate tool based on detected codes, improving the precision and efficiency of machining processes, particularly in dental milling applications.

Implementation Method 1

a sensor, in particular a spatially fixed optical sensor, has a detection range which overlaps the range of motion of the workpiece

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentUS11439484B2Method for controlling a machine tool
Publication Date: 2022.09.13 IVOCLAR VIVADENT AG
  • US11439484B2 patent drawing
  • US11439484B2 patent drawing
  • US11439484B2 patent drawing

AI summary

The invention relates to a system of a method for controlling a machine tool, and a workpiece, in particular a milling blank, and the method for machining this workpiece, said machine tool comprising a robot arm movable in at least 2, in particular at least 3 spatial axes in a range of motion, said robot arm carrying, guiding and moving at least one workpiece, possibly by means of a workpiece holder, with a control unit for controlling the machine tool. The machine tool (62) comprises a sensor, in particular a spatially fixed optical sensor or is assigned said sensor, whose detection range (66) at least partially overlaps the range of motion. The workpiece (10) comprises a change in geometry, in particular a hole (12), is moved in the detection range (66) by the robot arm (70), and upon detection of the hole (12) by the sensor the control unit determines a reference point, reference axis and/or reference surface for controlling the machine tool (62).