Linear Drive Mechanism for Shape Measuring Machine
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Solution Overview
Problem
Existing shape measuring machines face challenges in maintaining measurement accuracy due to issues with linear drive mechanisms, such as axial run-out in ball screw mechanisms and poor positioning retention in linear motor mechanisms, which can lead to reduced accuracy from external forces and vibrations.
Innovation Solution
A linear drive mechanism that includes a drive shaft, a mover supported by the shaft, guides positioned orthogonally to the shaft, and a resistance force generating portion, such as friction members, to regulate movement and prevent external influences, ensuring accurate positioning and reducing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ball screw mechanism is used to move the detector, then high positioning accuracy and durability are achieved, but axial run-out occurs during rotation which deteriorates measurement accuracy
Solution Approach 1:
The patent extracts the problematic rotating ball screw from the system and replaces it with a linear drive mechanism that eliminates rotational movement. The linear motor moves the detector along a straight path without rotation, thereby removing the source of axial run-out while maintaining high positioning accuracy through direct linear actuation.
Solution Approach 2:
The patent replaces the mechanical ball screw rotation system with a linear motor system that uses electromagnetic forces for direct linear motion. This substitution eliminates the mechanical rotation that causes axial run-out, providing both high positioning accuracy and measurement precision without the drawbacks of the ball screw mechanism.
2Measurement precision
If a linear motor mechanism is used to move the detector, then vibration and resistance are eliminated with high linear movement accuracy, but retaining force is insufficient causing the detector to move under external forces
Solution Approach 1:
The patent merges the linear motor mechanism with a guide structure that provides physical constraints. The guide rails or linear guides work together with the linear motor to provide both smooth motion (eliminating vibration and resistance) and adequate retaining force through mechanical guidance, thereby solving the problem of insufficient retaining force while maintaining high linear movement accuracy.
3Ease of operation
If the detector is moved by a linear drive mechanism, then positioning is achieved, but the detector is influenced by cable tension and piping weight which deteriorates measurement accuracy
Solution Approach 1:
The patent employs support structures such as cables or springs that counterbalance the weight of the detector and any attached piping. These anti-weight mechanisms compensate for gravitational forces and external tensions, allowing the detector to move smoothly along the linear drive mechanism without accuracy deterioration from unbalanced forces.
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 effectively suppresses reductions in measurement accuracy by regulating vibrations and external forces, maintaining high positioning accuracy for the detector, even when moving under external influences like cable tension or piping weight, thereby enhancing the precision of shape measurements.
Implementation Method 1
a resistance force generating portion which is provided on one of the mover and the guide, and is in contact with the other of the mover and the guide, the resistance force generating portion configured to generate a resistance force which resists against movement of the mover
Data Source
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AI summary
Provided are a linear drive mechanism capable of preventing deterioration in measurement accuracy of a detector, and a shape measuring machine including the linear drive mechanism. A linear drive mechanism which moves a contact type or a non-contact type detector having sensitivity in a first axial direction, relatively to a workpiece in a second axial direction orthogonal to the first axial direction, the linear drive mechanism including: a drive shaft extending in the second axial direction; a mover which is supported in a non-contact fashion by the drive shaft and configured to move along the drive shaft integrally with the detector or the workpiece; a guide provided at a position deviated relative to the drive shaft in a third axial direction orthogonal to both the first axial direction and the second axial direction, the guide parallel to the drive shaft; and a resistance force generating portion which is provided on one of the mover and the guide, and is in contact with the other of the mover and the guide, the resistance force generating portion configured to generate a resistance force which resists against movement of the mover.