Compact CNC Measuring Head Unit for In-Situ Precision
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Solution Overview
Problem
Conventional three-dimensional coordinates measuring machines (CMMs) are large, expensive, and unsuitable for in-situ measurements due to their large footprint and requirement for long measurement strokes, which are not always necessary for small or specific parts, and they interfere with machine tool movements when used for measurements.
Innovation Solution
A compact coordinates measuring head unit with CNC-driven probe movement along orthogonal axes, integrated housing, and fixture means for attachment, allowing high-precision measurements with reduced size and cost, and enabling in-situ measurements on machine tools and transport lines by separating the head unit from the base and stand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional CMM with long measurement stroke is used, then measurement precision is maintained, but device size and footprint become excessively large
Solution Approach 1:
The CMM system is divided into a movable head unit containing the probe and drive mechanisms, and a stationary base. The head unit can be positioned over different measurement locations, eliminating the need for a large continuous measurement space. This segmentation allows high-precision measurement of small or localized features without requiring a large overall device footprint.
Solution Approach 2:
The measurement capability is extended vertically by allowing the head unit to move up and down over the workpiece, rather than requiring horizontal travel over a large base. This dimensional change enables precise measurement of small features with minimal horizontal footprint while maintaining the ability to measure various heights and depths.
2Adaptability or versatility
If a conventional CMM with long measurement stroke is used, then measurement capability is comprehensive, but device cost increases significantly
Solution Approach 1:
The head unit is designed as a universal measuring device that can measure various features (holes, slots, contours, etc.) through programmable CNC control and different probe configurations. This multi-functionality eliminates the need for multiple specialized measuring devices, reducing overall system cost while maintaining comprehensive measurement capability.
Solution Approach 2:
The mechanical guide ways and precision mechanical components of conventional CMMs are replaced with CNC-controlled drive mechanisms that use motors and ball screws. This substitution reduces mechanical complexity and manufacturing cost while maintaining measurement precision through software-based positioning and error compensation.
3Measurement precision
If a conventional CMM is used for in-situ measurements, then measurement accuracy is maintained, but interference with machine tool movements occurs
Solution Approach 1:
The head unit is designed with independent drive mechanisms for each axis that can move dynamically without interfering with machine tool operations. The compact size and independent positioning capability allow the measuring head to be placed in the machine tool workspace without obstructing tool paths or chip evacuation, enabling simultaneous machining and measurement operations.
4Area of stationary object
If a compact CMM is designed for small measurement strokes, then footprint is reduced, but measurement speed decreases
Solution Approach 1:
The CNC control system enables continuous, high-speed movement of the head unit between measurement points without the need for deceleration and acceleration cycles typical of manual or semi-automatic systems. The programmable control optimizes motion paths and maintains constant velocity where possible, maximizing measurement speed within the compact stroke range.
Solution Approach 2:
Traditional mechanical feed mechanisms are replaced with high-speed motorized drives and ball screw mechanisms that provide rapid, precise positioning. The electronic control system coordinates axis movements to minimize cycle time while maintaining measurement accuracy, enabling high-speed measurement within the compact device footprint.
Data Source
AI summary
A coordinates measuring head unit is provided, which is compact, inexpensive, and capable of performing high-precision measurements at high speeds, and facilitates, for example, measurements conducted on machine tools or in-situ measurements on transport lines. The head unit includes: drive means (an X-axis drive section, a Y-axis drive section, and a Z-axis drive section), an integrated housing for accommodating the drive means, and fixture means (fixture surface). The drive means allows a probe to be moved by computer numerical control along a plurality of drive axis, which are orthogonal to each other, and abut against a measuring target to measure the dimensions of the measuring target. The fixture means is provided on one of side surfaces of the housing to attach one of the drive means to a support (a support on a stand secured to a base).