Process Signal Allocation to Workpiece Contours

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Solution Overview

Problem

Existing methods for contour-changing machining, particularly with tools like long end mills and cutter heads, struggle to accurately assign process variables to specific locations on the workpiece due to the large area of influence and varying spatial relationships, leading to deviations between actual and fictitious contours.

Innovation Solution

A determination method that assigns process variables directly to the area of influence rather than a single point, allowing for precise correlation with the workpiece's contour changes, using temporal filtering and volume data sets for accurate representation and evaluation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If process variables are assigned to the tool center point (TCP) to generate a polyline representation, then a sequence of points with associated process variables can be generated, but clear deviations occur between the actual contour of the finished workpiece and the fictitious contour represented by the polyline, especially when using tools with large areas of influence

Engineering Contradiction:
Improveease of process variable assignmentVSAvoidaccuracy of process variable location assignment
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent segments the area of influence into multiple discrete locations along the contour. Instead of assigning the process variable to a single TCP point, the method divides the tool's area of influence into several segment points that are distributed along the actual contour of the workpiece. This segmentation allows the process variable to be accurately associated with specific locations on the workpiece contour, resolving the inaccuracy problem while maintaining ease of assignment through automated calculation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a one-dimensional polyline representation (sequence of TCP points) to a two-dimensional area-based representation. By defining multiple locations within the area of influence and associating them with the process variable, the method creates a more accurate spatial mapping that reflects the actual contour geometry. This dimensional expansion from point-based to area-based assignment improves measurement precision without complicating the manufacturing process.

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

2Device complexity

If a single point (TCP) is used to represent the area of influence, then the assignment procedure is simple, but the spatial relationship between the TCP and the actual area of influence varies, leading to ambiguous assignment of process variables

Engineering Contradiction:
Improvesimplicity of assignment procedureVSAvoidambiguity in process variable location
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The patent applies local quality by defining multiple specific locations within the area of influence, each with its own spatial relationship to the workpiece contour. Instead of using a single TCP point that may be ambiguously positioned, the method identifies several discrete points (e.g., first location, second location, third location) that are strategically placed within the area of influence. Each location provides localized information about the process variable's effect on the workpiece, eliminating ambiguity while maintaining procedural simplicity through automated determination.

Inventive Principle:
Principle #3Local quality

3Area of stationary object

If the tool has a relatively large area of influence, then the tool can act on a larger portion of the workpiece, but the same section of the area is not always in engagement with the workpiece, causing deviations between actual and fictitious contours

Engineering Contradiction:
Improvearea of tool influenceVSAvoidaccuracy of contour representation
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by determining the area of influence dynamically based on the actual engagement between the tool and workpiece during machining. Rather than using a static fictitious contour based on TCP position, the method continuously identifies the actual area of influence as the tool moves and engages with different portions of the workpiece. This dynamic determination ensures that the contour representation accurately reflects the real machining process, maintaining manufacturing precision even when the tool has a large area of influence.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3454149A1Optimised allocation of process signals to contours of a workpiece
Publication Date: 2019.03.13 SIEMENS AG
  • EP3454149A1 patent drawingFigure 1
  • EP3454149A1 patent drawingFigure 2~3
  • EP3454149A1 patent drawingFigure 4

AI summary

By machining a workpiece (2) with a tool (1), the workpiece (2) is transformed from an initial contour (CA) to a final contour (FE). This machining process results in a process parameter (Pi). For each machining point (ti) during the machining of the workpiece (2), a process parameter (Pi) resulting from the machining of the workpiece (2) by the tool (1) at that respective machining point (ti) and a corresponding area of ​​influence (Ei) of the workpiece (2) are determined. The respective area of ​​influence (Ei) corresponds to a contour change of the workpiece (2) caused by the tool (1) at the respective machining point (ti). The respective resulting process parameter (Pi) determined for the respective machining point (ti) is assigned to at least selected areas of influence (Ei).The selected areas of influence (1) are determined such that they coincide with the initial contour (KA), the final contour (KE) and/or with at least one of the contours (K) of the workpiece (2) during machining.