Nonlinear Support Profile for Constant Beam Orientation in CMMs

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Solution Overview

Problem

Existing positioning apparatus in coordinate measurement machines (CMMs) suffer from deformation issues due to the application of loads, leading to variations in the orientation and height of beams, which affect measurement accuracy and limit the use of longer beams and larger objects.

Innovation Solution

The apparatus features a support with a non-linear profile that compensates for these deformations by maintaining the beam at a constant orientation and height through deformation, allowing for lighter and longer beams, reducing dynamic mass and improving metrological performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a long beam is used to measure larger objects, then the measurement capability is improved, but the beam deformation under load increases, worsening measurement accuracy

Engineering Contradiction:
Improvemeasurement capabilityVSAvoidbeam orientation accuracy
Core Design Contradiction:
Volume of moving objectVSMeasurement precision

Solution Approach 1:

The support profile geometry is changed from a standard linear profile to a specifically designed non-linear profile. This parameter change in the support structure causes the beam to maintain constant orientation despite position changes along the support, resolving the contradiction between beam length and measurement precision

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The support is given a curved non-linear profile instead of a straight linear profile. This curvature is specifically designed to compensate for beam deformation, allowing the beam to remain at constant orientation throughout its range of motion, thus enabling longer beams without sacrificing measurement accuracy

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Stability of the object's composition

If a heavy beam is used to maintain stability, then the beam orientation stability is improved, but the moving mass increases, worsening dynamic performance

Engineering Contradiction:
Improvebeam orientation stabilityVSAvoidbeam mass
Core Design Contradiction:
Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The natural deformation of the beam under its own weight is converted from a harmful effect into a beneficial one. By designing the support profile to match the expected deformation curve, the beam's weight-induced sag is transformed into a feature that maintains constant beam orientation, allowing lighter beams to achieve the same stability as heavier ones

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The support profile parameter is changed to a non-linear geometry that specifically compensates for the beam's weight-induced deformation. This allows the use of lighter beams with maintained orientation stability throughout the measurement range

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If a heavy support structure is used to prevent deformation, then the measurement accuracy is improved, but the device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidsupport structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of making the entire support structure heavier and more complex, only the profile geometry of the support is locally modified. The non-linear profile is designed to provide precise deformation compensation at each position along the beam's travel, achieving high measurement accuracy without overall structural complexity

Inventive Principle:
Principle #3Local quality

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 solution enhances measurement accuracy and enables the use of larger objects by maintaining beam orientation and reducing moving mass, thus improving dynamic performance and measurement capabilities.

Implementation Method 1

the profile of the support is deformed such that the beam is maintained at a substantially constant orientation for all locations of the beam along the support

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4413320B1support
Publication Date: 2025.08.20 RENISHAW PLC
  • EP4413320B1 patent drawingFigure 1~2
  • EP4413320B1 patent drawingFigure 3~4
  • EP4413320B1 patent drawingFigure 5~6(b)

AI summary

A positioning apparatus (100) comprising a support (108) extending in a first direction, and a beam (108) extending in a second direction. The beam (110) movably mounted to the support (108) so as to be movable in the first direction and exerts a load on the support. The support comprises a profile (302) which when the beam (110) exerts the load thereon the profile of the support (108) is deformed such that the beam is maintained at a substantially constant orientation for all locations of the beam (110) along the support (108).